Coping with Re-Homing... Suggestions Needed!

A year ago, my family had to make the heartbreaking choice to re-home our basenji, Phoebe.  She was about 8 years old at the time, and our family had recently grown to include a very busy toddler and new baby.  I knew that we were not giving Phoebe all the attention she needed, and she was starting to act out because of this problem. It was an extremely painful decision for us because we loved Phoebe very much, but ultimately we decided that she deserved a home where someone would pay attention to her more.  It would calm her behavior issues and help her to be happy again, and we loved her enough that we wanted her to be happy. 

When Phoebe first left our home, we told our son the truth about why and where she was going. We told him that we found a family that needed her to come be with them and love them. He has been fine for a year, but for some reason lately he has been very upset and sad about missing her. Any suggestions on how to help him?  He's four now, and I really want him to understand that Phoebe is happy and okay. 


Thank You,
Trisha Richardson