Hello Johan, would it be possible to get a DNA test for your father or an uncle or aunt on your father’s side? If the Ashkenazi history is your father’s, then the “signal” will tend to be stronger on a relative of an previous generation. If a grandparent or sibling of a grandparent is alive, that would be most helpful.
If you have cousins on your father’s paternal and maternal sides, testing them would help you identify which side carries the Ashkenazi history. I would say that Y-DNA will not help very much.
