Well..... as usual, we did not get the entire story.
There are site-owned condominium ownerships such as the op is describing here in Cali. Two townhomes, one common driveway, lot is split and owned by each unit. Maybe that's the situation that the op has.
Why the planning department of Glendale allowed the adu, mother-in-law's quarters, whatever it is, and how it conforms to zoning.....is baffling. There will be no comps. Not 10 miles out, not 10 years back. The OP is going to have to use SFR's with adu's....which is going to put him knee deep in s*it.
On top of all that, it's probably an AMC gig.