I note on SP there were two other children, with a gap of 8 years, maybe an earlier marriage?
Or maybe they moved around a bit - there are other baptisms around that time with father John Baxter in neighbouring parishes.
Magdalen Paul, born in Rothes in 1729, was one of 13 children of the Reverend John Paul and his wife Magdalen Innes. She and four of her siblings are listed on her parents' gravestone but no details of date of death etc. Interestingly, Fasti Ecclesiae Scoticanae lists only four of the daughters and none of the sons of Rev JP and MI, so it does look as if Magdalen may have died young.
M Paul who married Robert Humphrey appears to be Marjorie - Robert H and Marjorie P had a daughter Margaret baptised in 1750 in New Spynie.