Can I build an ADU on a Multi-Unit Dwelling that is zoned R-1?

[Bianca Ker]

I am looking at purchasing a property in LA County. The property has a main house built in 1916, and a secondary dwelling built (legally) in 1936. The property is an SFR R-1 but has 2 detached units, with an attached (to the main house) garage. I'd like to convert the garage and laundry room into a 1 bedroom ADU.

Multi-unit dwellings are allowed to add an ADU in LA now, without owner occupancy, but I'm worried the R-1 zoning may limit my ability to add a standard ADU (I don't want a junior ADU as I'd like to move out eventually). The law is a little fuzzy on multi-unit dwellings on R1 zoning.

Anyone dealt with a similar situation and had it approved?