my son who's 3 1/2 was diagnosed with SPD and "developmental"/high functioning asberger's and he often gets aggressive with his younger sister who is 20 months old. My question is when is it safe to start having them shares A room... She is beginning to be to big to be in ours but we have no other room for her except his. Any suggestions? advice please!!... Anyway to help the transition go smoothly would also be helpful. Thank you!