These room sharing tips will hopefully be helpful to parents to help make the transition easier on everyone!

Wait until the smallest child is sleeping consistently.  
If you can wait until your youngest is sleeping through the night it will eliminate most of the disturbances to the older sibling. It will also save your carpet being worn thin travelling in and out during the night!

Change your older child’s bedtime downtime location
Since the youngest goes to sleep first consider moving the older child’s downtime routine to your room.  Read their story, and your pre bedtime snuggle as you have always done, but just in another location.  Then sneak quietly into their own bed for sleep. It will make both kids feel a little special that they get their own time with your before bed.

Introduce your little one to their new room with a calming influence. A soothing noise machine and nightlight works wonders.  

Don’t forget the fun.
Chat with your older son or daughter about how fun it is to bunk with someone.  If you can afford it consider a little decor update it will add to the excitement. Ref number 2 above: maybe make the sneaking in part fun by pretending to be a quiet mouse or a secret spy!

Safety.
If your youngest is still in a cot, make sure they know they cannot climb out and make sure you tell the older sibling they are not to climb in or lob in objects/toys into the crib. They may think it’s nice to give baby a toy or a ‘blankie’ but these may not be suitable for young babies.
 
Adjustment time.
If any of the kids are struggling with the change, be assured that with time they will adjust. They just need a little time so stick with it. Soon the whole family will be sleeping soundly!