diff --git a/Project.toml b/Project.toml
index c4b8da7d..5e3b7ced 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "TidierData"
 uuid = "fe2206b3-d496-4ee9-a338-6a095c4ece80"
 authors = ["Karandeep Singh"]
-version = "0.12.2"
+version = "0.13.0"
 
 [deps]
 Chain = "8be319e6-bccf-4806-a6f7-6fae938471bc"
diff --git a/README.md b/README.md
index c9b2840b..949f1b55 100644
--- a/README.md
+++ b/README.md
@@ -78,7 +78,8 @@ To support R-style programming, TidierData.jl is implemented using macros.
 TidierData.jl currently supports the following top-level macros:
 
 - `@glimpse()`
-- `@select()`, `@rename()`, and `@distinct()`
+- `@select()` and `@distinct()`
+- `@rename()` and `@rename_with()`
 - `@mutate()` and `@transmute()` 
 - `@summarize()` and `@summarise()`
 - `@filter()`
@@ -106,6 +107,7 @@ TidierData.jl also supports the following helper functions:
 - `everything()`, `starts_with()`, `ends_with()`, `matches()`, and `contains()`
 - `as_float()`, `as_integer()`, and `as_string()`
 - `is_float()`, `is_integer()`, and `is_string()`
+- `missing_if()` and `replace_missing()`
 
 See the documentation [Home](https://tidierorg.github.io/TidierData.jl/latest/) page for a guide on how to get started, or the [Reference](https://tidierorg.github.io/TidierData.jl/latest/reference/) page for a detailed guide to each of the macros and functions.
 
diff --git a/docs/examples/UserGuide/fill_missing.jl b/docs/examples/UserGuide/fill_missing.jl
index a1b572bb..71d3a96c 100644
--- a/docs/examples/UserGuide/fill_missing.jl
+++ b/docs/examples/UserGuide/fill_missing.jl
@@ -34,3 +34,18 @@ end
     @fill_missing(a, "down")
 end
 
+# ## `replace_missing()`
+# The `replace_missing` function facilitates the replacement of `missing` values with a specified replacement. 
+
+@chain df begin
+    @mutate(b = replace_missing(b, 2))
+end 
+
+# ## `missing_if()`
+# The `missing_if` function is used to introduce `missing` values under specific conditions. 
+
+@chain df begin
+    @mutate(b = missing_if(b, 5))
+end 
+
+# Both `missing_if` and `replace_missing` are not type specifc.
\ No newline at end of file
diff --git a/docs/src/index.md b/docs/src/index.md
index 5ed7eff3..3c443d89 100644
--- a/docs/src/index.md
+++ b/docs/src/index.md
@@ -90,7 +90,8 @@ TidierData.jl currently supports the following top-level macros:
 ```@raw html
 !!! example "Top-level macros:"
     - `@glimpse()`
-    - `@select()`, `@rename()`, and `@distinct()`
+    - `@select()` and `@distinct()`
+    - `@rename()` and `@rename_with()`
     - `@mutate()` and `@transmute()` 
     - `@summarize()` and `@summarise()`
     - `@filter()`
@@ -120,6 +121,7 @@ TidierData.jl also supports the following helper functions:
     - `everything()`, `starts_with()`, `ends_with()`, `matches()`, and `contains()`
     - `as_float()`, `as_integer()`, and `as_string()`
     - `is_float()`, `is_integer()`, and `is_string()`
+    - `missing_if()` and `replace_missing()`
 ```
 
 See the [Reference](https://tidierorg.github.io/TidierData.jl/latest/reference/) page for a detailed guide to each of the macros and functions.
diff --git a/src/TidierData.jl b/src/TidierData.jl
index 7cac6701..833176ba 100644
--- a/src/TidierData.jl
+++ b/src/TidierData.jl
@@ -16,10 +16,10 @@ using Reexport
 @reexport using ShiftedArrays: lag, lead
 
 export TidierData_set, across, desc, n, row_number, everything, starts_with, ends_with, matches, if_else, case_when, ntile, 
-      as_float, as_integer, as_string, is_float, is_integer, is_string, @select, @transmute, @rename, @mutate, @summarize, @summarise, @filter,
+      as_float, as_integer, as_string, is_float, is_integer, is_string, missing_if, replace_missing, @select, @transmute, @rename, @mutate, @summarize, @summarise, @filter,
       @group_by, @ungroup, @slice, @arrange, @distinct, @pull, @left_join, @right_join, @inner_join, @full_join,
       @pivot_wider, @pivot_longer, @bind_rows, @bind_cols, @clean_names, @count, @tally, @drop_missing, @glimpse, @separate,
-      @unite, @summary, @fill_missing, @slice_sample, @slice_min, @slice_max
+      @unite, @summary, @fill_missing, @slice_sample, @slice_min, @slice_max, @rename_with
 
 # Package global variables
 const code = Ref{Bool}(false) # output DataFrames.jl code?
@@ -608,4 +608,55 @@ macro glimpse(df, width = 80)
   return df_expr
 end
 
+"""
+$docstring_rename_with
+"""
+macro rename_with(df, fn, exprs...)
+  interpolated_exprs = parse_interpolation.(exprs)
+
+  tidy_exprs = [i[1] for i in interpolated_exprs]
+  any_found_n = any([i[2] for i in interpolated_exprs])
+  any_found_row_number = any([i[3] for i in interpolated_exprs])
+
+  tidy_exprs = parse_tidy.(tidy_exprs)
+  df_expr = quote
+      local df_copy = copy($(esc(df)))
+
+      if $any_found_n
+          if df_copy isa GroupedDataFrame
+              transform!(df_copy, nrow => :TidierData_n; ungroup = false)
+          else
+              transform!(df_copy, nrow => :TidierData_n)
+          end
+      end
+      
+      if $any_found_row_number
+          if df_copy isa GroupedDataFrame
+              transform!(df_copy, eachindex => :TidierData_row_number; ungroup = false)
+          else
+              transform!(df_copy, eachindex => :TidierData_row_number)
+          end
+      end
+
+      local columns_to_rename
+      if isempty($(esc(exprs)))
+          columns_to_rename = names(df_copy)
+      else
+          columns_to_rename = names(select(copy(df_copy), $(tidy_exprs...)))
+      end
+
+      local renames = filter(p -> p.first in columns_to_rename, Pair.(names(df_copy), $(esc(fn)).(names(df_copy))))
+
+      if df_copy isa GroupedDataFrame
+          rename!(df_copy, renames; ungroup = false)
+      else
+          rename!(df_copy, renames)
+      end
+
+      df_copy
+  end
+
+  return df_expr
+end
+
 end
\ No newline at end of file
diff --git a/src/docstrings.jl b/src/docstrings.jl
index 5fc9a5e0..0cc2516c 100644
--- a/src/docstrings.jl
+++ b/src/docstrings.jl
@@ -2567,4 +2567,110 @@ julia> @chain df begin
    2 │ missing         0.3  missing   
    3 │       0.2       2.0        0.2
 ```
+"""
+const docstring_missing_if =
+"""
+    missing_if(x, value)
+
+Replace a specific `value` with `missing` in `x`.
+
+## Arguments
+- `x`: The input value which can be of any type. If `x` is already `missing` or equals `value`, the function will return `missing`. Otherwise, it returns `x` unaltered.
+- `value`: The specific value to be checked against. 
+
+## Examples
+```jldoctest
+julia> df = DataFrame(
+              a = [1, missing, 3, 4],
+              b = ["apple", "apple", "banana", "cherry"]
+            );
+
+julia> @chain df begin
+       @mutate(a = missing_if(a, 4), 
+               b = missing_if(b, "apple"))
+       end
+4×2 DataFrame
+ Row │ a        b       
+     │ Int64?   String? 
+─────┼──────────────────
+   1 │       1  missing 
+   2 │ missing  missing 
+   3 │       3  banana
+   4 │ missing  cherry
+```
+"""
+
+const docstring_replace_missing =
+"""
+    replace_missing(x, replacement)
+
+Replace `missing` values in `x` with a specified `replacement` value.
+
+# Arguments
+- `x`: The input value which can be of any type. If `x` is `missing`, the function will return `replacement`. Otherwise, it returns `x` unaltered.
+- `replacement`: The value to replace `missing` with in `x`.
+
+# Examples
+```jldoctest
+julia> df = DataFrame(
+              a = [1, missing, 3, 4],
+              b = [4, 5, missing, 8]
+            );
+
+julia> @chain df begin
+       @mutate(a = replace_missing(a, 100),
+               b = replace_missing(b, 35))
+       end
+4×2 DataFrame
+ Row │ a      b     
+     │ Int64  Int64 
+─────┼──────────────
+   1 │     1      4
+   2 │   100      5
+   3 │     3     35
+   4 │     4      8
+```
+"""
+
+const docstring_rename_with =
+"""
+     @rename_with(df, fn, exprs...)
+
+Renames the chosen column names using a function
+
+# Arguments
+- `df`: a DataFrame
+- `fn`: desired function to (such as str_remove_all from TidierStrings)
+- `exprs`: One or more unquoted variable names separated by commas. Variable names 
+can also be used as their positions in the data, like `x:y`, to select 
+a range of variables. Variables names can also be chosen with starts with. Defaults to all columns if empty.
+
+# Examples
+```jldoctest
+julia> function str_remove_all(column, pattern::String)
+         if ismissing(column)
+             return column
+         end
+         patterns = split(pattern, '|')
+         for p in patterns
+             column = replace(column, strip(p) => "")
+         end
+         return column
+       end;
+
+julia> df = DataFrame(
+              term_a = ["apple", "banana", "cherry"],
+              document_a = ["doc_1", "doc2", "doc3"],
+              _n_ = [1, 2, 3]
+            ); 
+
+julia> @rename_with(df, str -> str_remove_all(str, "_a"), !term_a)
+3×3 DataFrame
+ Row │ term_a  document  _n_   
+     │ String  String    Int64 
+─────┼─────────────────────────
+   1 │ apple   doc_1         1
+   2 │ banana  doc2          2
+   3 │ cherry  doc3          3
+```
 """
\ No newline at end of file
diff --git a/src/missings.jl b/src/missings.jl
index 3226d362..6af74d42 100644
--- a/src/missings.jl
+++ b/src/missings.jl
@@ -115,4 +115,14 @@ macro fill_missing(df, args...)
           fill_missing($(esc(df)), [$(cols_quoted...)], $method)
       end
   end
-end
\ No newline at end of file
+end
+
+"""
+$docstring_missing_if
+"""
+missing_if(x, value) = ismissing(x) ? x : (x == value ? missing : x)
+
+"""
+$docstring_replace_missing
+"""
+replace_missing(x, replacement) = ismissing(x) ? replacement : x
diff --git a/src/separate_unite.jl b/src/separate_unite.jl
index 22817003..b8dbec3a 100644
--- a/src/separate_unite.jl
+++ b/src/separate_unite.jl
@@ -61,14 +61,24 @@ end
 $docstring_unite
 """
 macro unite(df, new_col, from_cols, sep)
-    new_col = QuoteNode(new_col)
-    
-    if @capture(from_cols, (args__,))
-    elseif @capture(from_cols, [args__])
+    new_col_quoted = QuoteNode(new_col)
+    interpolated_from_cols, _, _ = parse_interpolation(from_cols)
+
+    if @capture(interpolated_from_cols, (args__,)) || @capture(interpolated_from_cols, [args__])
+        args = QuoteNode.(args)
+        from_cols_expr = :[$(args...)]
+    else
+        from_cols_expr = quote
+            if typeof($interpolated_from_cols) <: Tuple
+                collect(Symbol.($interpolated_from_cols))
+
+            else
+                $interpolated_from_cols
+            end
+        end
     end
-   
-    args = QuoteNode.(args)
-    var_expr = quote
-         unite($(esc(df)), $new_col, [$(args...)], $sep)
+    
+    return quote
+        unite($(esc(df)), $new_col_quoted, $(from_cols_expr), $(esc(sep)))
     end
-end
+end
\ No newline at end of file