I gave the original school lot in Sunset Valley a makeover and build 2 houses, one representing an elementary school, the other one a high school. I also placed two rh rugs and gave them different names with DebugEnabler. So far, so good. But when I want to assign teens and children to those rugs with MC, both show up under the lot adress and I can't tell them apart. Also, I can't see a way to automatically assign the age groups to the two rugs in SP.
Is there a way to do this or do I have to rebuild the whole thing and put the schools at different lots?

There might be a sneaky way to rename one or both of those rabbit holes, but that's the lesser of the problem with that structure. School registrations assigned by age group or some other such criteria require SP Lot Options caste restrictions, thus unless you want to constantly manage the town's enrollment with MC for each student as they arrive, become children, and become teens,  the different schools must be on different lots. Note that the GoHere mod also be present for the Lot Options to be honored.

Edit: Perhaps this FAQ helps?

Not the answer that I hoped for but thank you. Back to building then. Sigh.

Sorry about that, then. Don't know if you are looking for building layout ideas, but I've started putting school rabbitholes in more creative places recently. In one world, the elementary school is in a second library, upstairs from the general reading areas, teens can use the original library for other purposes, and that's worked out great with both libraries still being very popular places. In another world, I've been thinking about putting the high school on a graveyard but then it would have to be a "no children" graveyard to get sims to honor the Lot Options restriction. Not sure if that one will work out as well, still thinking it over. 

I would place library zoned lots in a few different locations so that one is in he town center and others are in other locations.I also have manual assignment to schools so any children or kids living near a school rabbit hole can be enrolled in the nearest one to their home while those without a school nearby just get home schooling or have no schooling at all.I intend to have schools assigned by catchments with students being from homes near the schools they attend after being enrolled.I use awesommod to disable all automated school assignments to help make sure nobody ends up attending the wrong school unless they forgot to get that changed when they moved or the child aged up and forgot to switch over to home schooling before moving out on theit own.

I actually want to keep the number of community lots low so I'm combining as much as I can.

I also used all my building mood for that lot so I gave it a try, removed one rug and opened the other one with Zerbu's Ultimate Careers mod. After a few changes in furnishing, it runs surprisingly well with all children, teens and teachers roaming and working there.