As to your mortgage, the collateral is still the home at xyz street, only difference is you are now lacking income to help pay or was used in qualifiying you for the mortgage you presently have. Bank still has same colleteral and you still have the same obligations.
You also don't mention if permits were pulled for the work done. There is plenty to think about, but I would keep it's legal usage as a multi and pay the extra property taxes, which you may deduct from your taxes. Either way, good luck with what you decide to do.
Dan Derito/ Keller Williams Realty
If you didn't do it in the permitted fashion you may be in quite a predicament and should consult with an attorney immediately to review your legal options,
Hope that helps
Wil be rezoned by the city or county, that helps. If you have done it without permits then you refi, an appraiser comes out, and appraise it based on a single family residence.
You can also talk to your current lender, which may or may not be competitive.