The puppy should probably not cause any problems until she is up over a year, and actually, the age difference may make all the difference, as they are raised together.
Right now that baby is just a baby and wants to play. The old dog is OLD, and her joints and body can be hurt by a rambunctious puppy, so she is probably letting the baby know what she can and can't do. Keep an eye on it.
When the pup is mature, in two years, your mix may very well be still around as 15 is not out of the question. It will make total sense to crate one or the other when you can't supervise, and come down on the pup if in your presence she starts giving the old one trouble.
If worse comes to worse, which is actually pretty unlikely, considering the vast differences between the two, specifically age and power, you may have to crate and rotate.
But just because of the age of the Old Lady, and the youth of the pup, it makes sense to separate when you cannot supervise, and pay attention. If the pup is getting on the older ones nerves or body, it makes sense to give them a break from each other, until the baby realizes that playing nice, and being gentle means one thing, and getting crazy means another.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC
Hepzibah & Hannah