If you are willing, wean the 2yo off the night feed. Make it a grand event to drink a bit more before bedtime, set up a reward system to get stickers or something if your child sleeps through the night. Make it an even grander affair for your 2 children to move into the same room. Make it fun and exciting for them. Create a new bedtime routine with your children, to drink milk together/read stories together and go to sleep together, then ask your 4yo to remind your younger child that both of them will not need to wake up for milk and daddy and mummy will see them in the morning. I’ve had 2 kids crying (including a newborn) in the middle of the night before. It’s exhausting. If you can help 1 to break out of that habit before the new baby arrives, that will help you greatly:) And I really do think you have just the right amount of time to wean your 2yo off the night feeds, and then the moving rooms. It may require some crying and some comforting (other than feeding), and some rewards, but you can do it 💪🏻!
Is Helper co sleep with 2 or 4 yo? You can consider either helper or husband sleep with 2 yo in 1 room. Help to do 1 time night feed. Discuss with them. They can do alternate week / month? So , 4 yo still remain sleep separate room. You can fully tc of newborn baby at night. It’s better. After birth you will be quite exhausting.