Forename NN OR Greta Martha
It would be fantastic if we had found her name. Penelope du Toit, do you have the Sources for this name?
There is another problem
Bertholds son Heinrich became Provost to Schleswig / Lubeck.
Ketel died in 1520 and was succeeded by Benedict von Ahlefeldt
If Heinrich Ketel really died in 1520,then he could not have had the child that would eventually marry Bernd because she was supposedly only born in 1540. This is another problem.