I know that there is only a slim chance of you still being at this e-mail address, but I too am researching Berton and Lisser Gottheimer in the UK and in Prussia. Is it possible you could tell me what your link is. I am guessing it is through Maurice or Abraham/Albert, as Lavinia did not marry, or so I believe.
I would love to hear from you and if you have a Gedcom file that would be wonderful.
I am in the UK by the way