I limit the time a new pup spends with the older dogs. His center of the world should be me. I have always given them play time with the others but only a few times a day. You have to take him on socialization outings, puppy class by himself so he develops a bond with you and can develop his confidence without having to rely on the other dogs. If I am working with a new pup, the older dogs are crated and cannot interfere.
You have to be careful with the IG when your pup is getting stronger. I am talking from experience.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015