As the scenes selection in the flow card work with a so called “autocomplete” function in homey to get the full list in the flow card (you really need to select/click an option), makes it impossible to do what you want unfortunately.
the easiest way is to create a separate flow for each option you want
That would indeed be the way to go. (And having to flows is also very clear)
Make two flows with the different livingroom_{state} setting in the THEN. (Flow A and flow B
for selection off the correct flow you habe two options:
1 disable/enable the flows based on the state [MORNING, EVENING…]
Flow A: when switch is pressed THEN set livingroom_MORNING
Flow B: when switch is pressed THEN set livingroom_EVENING
IF a value is changed “state” AND state=morning THEN enable flow A, disable flow B
IF a value is changed “state” AND state=evening THEN enable flow B, disable flow A
2 use the AND to select the correct flow