Biting

So my 3 year old has been biting his little brother a good amount but normally on the back or on the arms. Once on the legs. I put them to sleep in the same room last night because we are moving and my 1.5 year old woke up and had been bitten on the cheek by his brother. Normally the 3 year old only bites when he has to share and I assumed because my 1.5 year old was in a pack n’ play that he would be fine. He also flipped the pack n’ play accords the room. We are trying to get the 3 year old in therapy but it is a difficult road because most people won’t see him this young. His dad is deployed and we are obviously moving so his life is hectic. Has anyone dealt with this. I am moving them to separate rooms again.