We have a multi story mixed resi.
First floor, stairway, and common use exterior are one system.
Second floor brother family #1
Third floor brother family #2
Not planned for continual use as of now. Vacation beach property.

My question is best way to setup systems in particular the common area and more to the point the
access to change time clocks for the common area.
As of now it's unclear if the network will be one full system with subnets or three or two....?
Looking for advice to guide the owners if need be.
If they put the common area on brother #2 system but brother #3 is there and wants to control common area?
If they have to change to a diff WIFI to work each systems it may get a little confusing.

See where I'm going?