I wonder if I could elicit some assistance in cleaning up a family tree of my 6th great grandfather

I would like to confirm dates and marriages of the six children of Joost and Margretha Loucks of German Flats. There may have been more children but the six I have are the ones most researchers agree upon.

I am mainly interested in the confirmation of and dates for the marriages of Gertrude, David (to Abigail Gray), Peter H, Johann George (George), and the multiple marriages of Joseph Joost Loucks.

I am unable to find any what I consider primary sources online.

Kind regards,

Neil stumped in Arkansas.