Ditmer Family Genealogy Forum
Sorry that I cannot be of any help to you on your line of Dittmers. I have traced my line back eleven generations to Andreas Dittmer who was born c1595 and lived at Reiterswiesen, a small village now in the far north of Bavaria just over the hill from the resort city of Bad Kissingen. My greatgrandparents were born in this village in the 1830s and emigrated to central Iowa in 1859. I have had access to all of the local Catholic church parish registers which recorded birth/baptisms, marriages, and burials back to the early 1600s.
Your line in Hannover appears not to be from that area.