Hi,
"Barbara though seems to be the only child of theirs born on edrom!!"
I can't find this Edrom birth for Barbara, but is this the Aberdeen family you mention? All dates are for baptisms in Strichen, spelling variations for Elspet shown.
George Anderson married Elspet Fouly 7th Jun 1767, Strichen, Aberdeen
Children:
Mary Anderson 2nd Jun 1768 – Elspet Fowlie
Margaret Anderson 18th Feb 1770 - Elspet Fowlie
George Anderson 27th Jun 1771 - Elspet Fowlie
James Anderson 12th Apr 1773 – Elspet Fowly
Isobel Anderson 30th Apr 1775 – Elspet Fowly
Janet Anderson 30th Mar 1777 – Elspet Fowly
Barbara Anderson 17th Sep 1778 – Elspet Fowly