not sure what direction you are researching but
have john Gell + margt (fam name Unknown) had son Nicholas
Nicholas + Isabel Kenniagh(d/o Thomas Kenniah + Margt of Kk German) had dau Isabel
Isabel Gell + Thomas Callister had only child Sivester (bapt 1764) (Thomas m a 2nd time but ?no children from 2nd marr)
various marriage contracts, will summaries etc on MNB or MNC cd - suspect land records in Kk German + Kk Patrick (many of which are on my cd will get you back a couple more generations)