Combining smart switches and sliders (2 entities in one card)

[Ewoodster]

Hello,

I just found the lovely slider button card yesterday, yet I got some issues to solve.
My house is equipped with a combination of smart switches and smart bulbs. The smart switches turn on or off the voltage to the bulbs.

Therefore I need to combine two entities in the cards: The switch and the (group of bulbs) bulb. How can I make this work?

It doesn't work reliably if I include the switch in the light bulb group.

Any help is appreciated