Nothing you are describing sounds like dominance. It sounds like a normal adult dog adjusting to the new addition. Until they work out the relationship, which they need to do on there own, you need to intervene, separate and make sure Charger is still getting the same amount of attention and affection from you. I have yet to see an adut dog who welcomes new puppies with open arms, all of my girls snarl, growl and warn puppies to back off. It takes time and a lot of supervision.
I have a 9 year old lab and a now 2 year old and occasionally the older one still raises her lip at the younger one, she is annoying, full of energy and she bugs her. They are not best doggie friends, never will be but they co-exist peacefully and I still pull the younger one away if she is determined to really bug my older one. I also have a corgi who is more like my younger lab in terms of energy and playfulness so that distracts her most of the time away from my older lab.