Storm and Angel got on perfectly when we added aurora.
That was never an issue, Angels insistence to not have another dog in the pack was a huge issue.
The girls even now years on have fights, proper fights over food. I have to be so careful, so careful. I have several new scars from breaking up fights. Would I get rid of anyone? No of course not. My kids are old enough to know to not interfere if they do fight and we manage them perfectly.
Integrating a newbie especially a pup is very hard.
What we did was basically make pup bottom of the pack BUT ensuring the dogs knew she belonged to us. A lot of claiming her as mine happened.
Treats went in order and still do now, storm, Angel and then aurora. Everyone sits and paws.
Its not undo able. But don't think that a pup will fix issues already underlying.
Hope I've given some help lol x
P.s. Are you sure you want a red????
You know they're crazy right??