Hi,
I wouldn't really concern yourself about the 'shift' in job titles. After all, you'll have other things that will be more immediate....like puppy accidents :D :D :D :D
IMHO: Mother/dominant bitch = same level of respect :) Chienne was 'mothered' by Samma when I first got her as a tiny puppy. She slept next to her and as she grew, the mothering shifted into buddiedom :) Still unseparable. Now that Samma's getting a bit slower, esp. when sleeping, Chienne is taking over the 'watchdog' job position. The same happened with Pepper 'retiring' when we got Samma. :)
I look forward to 'hearing' about your experience. Have fun with a new puppy :D :D
toodles