When you are picking by UIDs in sub-events, you need to add "For each Buildings" loop to the parent "is overlapping" event. Otherwise your code will only work for the first building/player instance.
I have two very simple demos for z-sorting, check them out:
Thank you very much, Dop2000.... Can you believe that the same happened as the other day?: I figured out what you just said 20 mins before I got the email with your answer. Really funny.
Again, that it's great because it tells me I'm on the right track.
It's also funny that the tutorials about families that are around in the site are AWFUL. With no bad intention I can say 2/3 tutorials I've read were wrote by people that didn't actually fully understand their craft.
I'll download and check your demos shortly to see if there's more I can improve.
Now it's lunch time.