3 buttons 3 functions


I would like to create 3 different functions with 3 different buttons in an already existing program.

1 button for starting the existing program, and 1 button for stopping it.
I would also like another button for starting another “program” in this already existing program, but this smaller one will be prioritized.

Do you have any suggestions on how to do that?
Any suggestions are appreciated!

Thanks in advance

Kind Regards