Turn converted space into duplex

[Lee Gaines]

Hello all, what do I do? We purchased a home 3 years ago in Modesto, CA that already had detached garage converted and built into 2 bd, 1 ba apt. The space wasnt included on sq ft description of home i believe because it was built many years ago. My question is how do i get it officially approved for its own address/ making this a multi unit location. We bought to have space for aging grandparents and would love to be able to rent out.. legally.. Thanks for all the help!