Mobley Family Genealogy Forum
Are you aware of Christina Biddle having a sister named Sarah?
I just posted a reference to the Moberly Family Forum about the will of Zephaniah Harrison leaving a bequest to "my late wife's sister's daughter, Sarah Moberly, daughter of Denton Moberly, of Juniatta in Pennsylvania" (see Frederick County, Maryland. Will Book H S-2 P. 283).
There is a marriage of a Sarah Biddle & Saphenia Harrison in October 1793 in Frederick County, Maryland and I thought they might tie into your family tree.