Mother's maiden name- Elizabeth Clayland Tomlinson
Father's name- William Barclay Foster
Wife- Jane Denny McDowell (later remarried- Wylie)
"by her family" ..."addressed by the affectionate diminutive 'Jennie'" says Morneweck in "Chronicles ...." (link by Masato).

I wonder if there an affectionate name for Foster's mother, Elizabeth?

leeneia, in what song collection did you find Jennie, the child?