So now I know that the woman listed with the family in the church register is NOT the mother of the children. But another interesting finding is that one of the children listed, Cornelia, actually died in the Netherlands and never was at the North Holland Church!
On the 17 April 1866, Cornelia Morren, age 14, daughter of Willem Morren and Lubbertje Hop, deceased, died. It reported and signed by Willem Morren, father. Signature is the same as on his marriage record.