Third child- room situation

Hey all! So this baby is baby number three for us. I have a three year old and a 16 month old. Currently baby is sleeping with us but he is growing out of his bassinet quickly and I feel needs to be in a crib ASAP! We have a three bedroom house and I cannot figure out the room situation. My 16 year old son has been randomly waking up crying and my three year old daughter wakes up randomly crying and fights us on bedtime too! So I’m worried they will all wake each other up no matter who shares. Any suggestions???