Is the quit claim deed void or partial void when the deed made with 1 signature real but the other signature forged? The rental

owned by 3 (me, my husband, his sister) then the quit claim deed (without compensation) to his sister signed by him but my signature forged by someone else. I found lately. Now only sister-in-law's name on title and mortgage, she refinanced and got some cash without sharing with others, lender and title company did not know the problem of deed either. Will title be recovered back as original (before forged quit claim deed) all 3 in joint tenancy? Or part (forged signature) of quit claim deed void but part transferred? May the problem be fixed without going court ("quiet title" taking time) and how? Who (lender or title company) may correct title and mortgage? The loan is behind lender'll foreclose soon. Please advise some ways in addition to deal with her. Thanks.