i wouldnt worry to much about it, i have a 4 month old female pit and a 8 year old wolf husky shepherd x and thats all they ever do.
Alice (my pit) is always wanting to play, but my older dog will growl, push ect ect but its not like she wants to kill her, its because shes trying to teach her her own boundaries.
Just like us, dogs have there limits, for example, i saw alice trying to sneak a bite out of the garbage yesterday, i immediatly corrected her, showing that i DO NOT want that, just like your older dog, she DOES NOT WANT a puppy jumping at her face, so she’ll let her know, after awhile and once the pup relises the older dog is not interested, she’ll move on.
But always give your older dog a helping hand, if the pup is jumping at her face tell her “no jumping!” or get her attention with something else, dont reward her for it tho, you dont want her thinking jumping up is a good thing.
I definatly dont think its a disaster waiting to happen, i’ve always had more then one female dog, usually pit bulls to. What your older dog is basically saying is your a puppy, im not, dont treat me like im a puppy because im not.
Im really sorry to hear about your dog passing away, i understand how hard that is.
Just keep up with corrections, routine, exercise and love and you and your dogs will be much happier, like the saying goes, a good dog is a tired dog.