I could not find her birth in the Llanidloes Registrars.
Llanidloes Parish Church
1790 Richard Jenkin, bachelor, marries Mary Morris, singlewoman, at Llanidloes Parish Church, and both are "of the parish". Married by banns on 24 May 1790. In presence of Evan Evans and Lewis Richards.
1797 John Jenkins their son was born. So one would assume that there were other children born before and after John.
Family Fan Chart