****-A-Poo Biting other family members

Our 1st ****-A-Poo, Mclovin passed away several months ago and we got a new 14-week-old pup (Chester) from a local breeder who takes a long time to get back to me with answers to questions I might have. At first, Chester totally attached to me, and over the last 30 days has become more equally attached to my wife. However, he will attempt to bite my 3-year-old grandson who is very loud and aggressive but Chester is also scared of my 10-year-old Grandaughter and my 38-year-old daughter. He will bark at them or nip them if they try and interact with him. He will normally just avoid them. This is the only problem we have with him and he is very intelligent. We have not socialized him outside yet as we just got his rabies shot 2 weeks ago. We will not be having him neutered until he is at least 6 months old, probably more like 8 months old. and now will be starting to take him on walks around other people and dogs to get him used to it. Any suggestions would be appreciated as having him bite my grandkids in the future would be unacceptable and would cause us to consider re-homing him which I would hate to do as I am getting very attached to him.
Al