It has now been scientifically proven that the so called 'pack structure' in the pet dog does not exist, and that dogs are not always on the look out to become pack leader over the other dogs or the owner. Unfortunately some so called trainers still think along these lines, and then employ the 'dominance' theory to it, which can cause all manner of problems, where none existed before.
Dogs will push themselves forward for something depending on how much they want it, which is why some people say they can't make out who is in charge. It just depends if one dog is say more food orientated or another more toy, or affection. Dogs will usually take a lot from puppies, precisely because they are puppies. However as the puppy grows, then they may become less tolerating with the adolescent dog. It sounds as though your dogs are pretty normal to me, so don't make a problem by worrying about something when there is probably nothing to worry about.