My fourth-born had this same issue... All of my kids share a room because they are extremely close in age and just like to be together, so we turned the nursery into a play room and decked it all out beautifully, so we do not want to change it until we are ready for it to be a permanent change. We have other bedrooms, but they're all in use until the kids are ready to be separated permanently, too. Anyway, our fourth-born refused to sleep in the kids' room, and even if he was finally able to fall asleep, he would wake up if they made the slightest peep. Just like your baby, he was self settling fine before the move, but he would just scream until all of his siblings were wide awake if he was in their room. We did end up moving him into a pack 'n' play in the playroom, and he self settled and slept fine in there. If we didn't have a playroom, we would have kept him in the hallway since there's no good place to put a pack 'n' play in my bedroom, and he could climb out of the bassinet. We let him sleep there for 2 months to let him adjust to being in a room without us before moving him back to the crib in the room with his siblings. He would still cry! We asked the kids to brace themselves as he readjusted to the room, and he cried through the night for two entire nights. (I use the Pick Up/Put Down method, so I would go in and pick him up and then put him right back down to bed... all night... for two nights... and then he only woke a little the third night.) If I'd disassembled the crib, I would have left him in the playroom permanently, but I didn't want to take it apart any more than I needed to since has been used for so long, so I dealt with this. After the few nights of crying, though, he slept in there wonderfully. He is 15 months old now, and this adjustment started at 8 months. After a few weeks, he loved being in the kids' room, and he especially LOVES sleeping in the kids' room now, and even if I tried to move him, he wouldn't allow it. In fact, I put him in a pack 'n' play one day when his siblings were all sick, and he climbed out and got into bed with his oldest sibling.
