Tryntje Sybolts, the first mother, married her first husband, Hindrik Jans, at Uithuizen on 31 Oct 1762. 

Wil Kruizinga found in the archife in Groningen in the DTB boek of Eppenhuizen, that Hindrik Jans died 8-6-1765 in a house for poor people in Eppenhuizen. 

So Tryntje and Hindrik's marriage was short-lived.  They shared one child together (Tryntje in 1763).  But what became of Tryntje, the mother, after Hindrik passed?  Assuming that Jacob Cornelis was born in 1765, she was with child at the time of Hindrik's death.  It just wasn't Hindrik's.  She must have been impregnated in Eppenhuizen.  But by whom?  And where did the surname Cornelis come from?

Those are the major questions to which I seek the answers.  And I believe I will.