Switching/sharing rooms

I have two kids almost 4 and 2.5. I’m expecting my third early December. The two oldest will be sharing a room but I’m nervous because the oldest needs me to cuddle her till she falls asleep and wakes up every night to come into our room where as my son sleeps all night on his own and still sleeps in a crib.

My question is do you think that my oldest would do a lot better with her brother in the room (I think she just doesn’t like to be alone) or is my sons sleep going to take a hit. I’m also worried about putting him in a normal bed when he sleeps so well in the crib. I was thinking of doing it during the summer when they’re extra tired from running around and plenty of time to get used to it before the new baby comes.

Any tips or advice? Thanks 😊