Is it possible to introduce a baby into a toddlers room when she's stopped self soothing?

[weeblueberry]

DD1 used to self soothe really well but, with toilet training, has been very unsettled and now won't self soothe at night. Instead she gets read to sleep and goes that way.

We want to introduce the baby to the toddlers room but I've no idea how bedtime will work? Currently the baby gets fed to sleep and I suppose, normally, the toddler can be put down while I'm feeding the baby in our room which will give her time to fall asleep and then the baby can be put down. But on nights like tonight the toddler has had an errant nap and it will take a while to get her down.

Does anyone have experience of this? The baby really needs to move out our room because she and I are waking each other. The toddler has been away the last two nights and the baby being in the other room by herself has resulted in only a single wake in the night. The other reason for the move is that the toddler is coming into our bed in the night which means DP isn't sleeping. So we've got a wee mattress thing she can sleep on but there's not enough room for that and the cot.

I really don't know what to do so would appreciate any advice.