inaccurate merge

I have recently been bombarded with mass merges in several of my lines. Most of them are leaving me with totally incorrect relationships. I have managed to fix some of them but not all. One merge left my 2x great grandfather Isahm Johnson Davis with the wrong parents. I had his parents as Unknown since I wanted to connect him with his known siblings. Now both he and his siblings have the wrong parents and I do not know how to fix it. If I disconnect him from his parents his siblings will still have the wrong parents. I do not know how to get them all back together with Unknown parents.  I think I need a curator.