Personally, my children took it very well and had somewhat of a full grasp of the idea and concept. Our last journey they were 3, 7, and 10 when we transferred and was successful. The entire pregnancy we always talked about the baby in the terms of "___ and ___'s baby", since the IPs were able to visit a few times, they were able to put faces to the names and formed an amazing bond with them.By the time delivery came, they fully knew that this was not going to be their "brother" but simply a baby for another mom and dad. Since birth, we have kept in contact and the kids get to see them through skype. I was personally very surprised how well they actually understood what was going on and that the baby was not related to us. I think you will be pleasantly surprised too :)!