Just use 'else', thats why it is for.
New top-level event ...
Condition > on powerup clocked
.....................do all the stuff you need
New top-level event ...
Condition > on house clicked
.....................do all the stuff you need
For me (personal) this a bit of a PITA. I have troubles reading this code and they need to stay a pair when i start moving events arround. So i usaly do ...
New EMPTY top-level event
....Sub event with the conditions ...
....Condition > on powerup clocked
.....................do all the stuff you need
....Sub event with the conditions ...
....Condition > on house clicked
.....................do all the stuff you need