Edge will be the replacement for device controllers, but it’s still in Beta. (The topic title is a clickable link.)
There is a community-created edge driver available that has a virtual presence sensor if you want to go ahead and try that but that doesn’t solve your question about how to set up the rules.
As far as the replacements for rules, there is increasing complexity being built into the default rules engine when you create a routine through the smartthings app, or there is something new called the rules API, but I will leave it to others to discuss that option.
@Automated_House may know if there’s a way to do what you want using the default rules engine.
If it’s not possible to have multiple presence tested in an If, I would think it would be possible to use a virtual sensor which is both a Switch and a Presence sensor (the edge driver I linked to is one of these) and then test for the switch portion being on or off.
So
If
self switch is off
Spouse switch is off
Child switch is on
Then set up house the way the child wants.
But I don’t know for sure that that works, others should be able to say. That’s how I used to use presence when I used a virtual presence sensor, but it’s been a while since I’ve tried to set up a routine in the smartthings app. (It’s not voice navigable, so I can’t do much with it.)