Will freely admit I'm no language expert either, but I'm getting my information from an expert who is also an anthropologist. My focus has largely been on Aryan origins which has taken crazy turns, including the origins of Jews and the biblical tribes. The anthropologist has presented standardized charts showing the etomology of language. Yiddish is definately the predessor language to Old German. I believe middle German follows Old German. Meaning Yiddish -> Old German -> Middle German -> ... Regardless, these general topics (history) are something I've been working on for decades. Though the Aryan topic is much more recent. That said it has tied into much other origin research with little conflict. As for the Askenazi, they would use whatever is required of them at the time. Personally I find them largely irrelevant for language origins. Though feel free to disagree. You may find the link I shared with others here of interest. Read all comments and find the link I repeatedly shared. Here is something to think about with the Ashkenazi. At they time they declared themselves Isrealites, no one raised a brow that a large group of Caucasions declared themselves Isrealites. This will feed back into the link I mention above. As a side note, as for the ancient Egyptian language ties, even some Jews are recently making these claims to Hebrew. Yiddish <-> Hebrew has commonalites. You can see where this goes. Latly, I would like to say thank you for disagreeing so politely. Much appreciated. Even if we continue to disagree, I'm happy to return the respect. Cheers