2 homes on 1 lot - zoning issue?

[Brad Birchfield]

Hello - has anyone encountered this situation before?  I found a property in Johnson county, Texas (south of DFW) that has 2 inhabitable structures on 1 lot.  There is a main house and then a separate garage that has an apartment.  The lot is currently zone as residential.  The house and the garage apartment have separate meters.  I know you are not my lawyer and that I should consult a local lawyer that is familiar with the city's zoning ordinances, but do you know if this is risky?  Can the city force me to tear down the garage apartment, not rent it out, or anything else since the lot is not zoned multifamily?  The property does not make financial sense without being able to rent out the garage apartment.  I suppose I could always request rezoning or a special use permit from P&Z later on, but I would like to get some answers now before I go under contract.  Thanks!