Is your feature request related to a problem? Please describe.
I cannot figure out how to add two commands to one button press.

Describe the solution you'd like
Tell me how plz

This is already implemented but not available over the UI yet.

If you urgently need this, you can store a NPC preset and edit the preset file with any NBT editor to add additional actions on a button click or so.

The relevant part inside the preset file is: