Buying at auction and release of judgement mortgages

If the bank sells a commercial property, "mortgagee in possession", and their charge is not fully satisfied, it keeps the entire proceeds. (I assume). From the original borrowers point of view, what happens the judgement mortgages, (including one from revenue) on the premises, if his only other asset (his house) is in negative equity and also subject to the same judgement mortgages.