Welcome to WikiTree Valerie. Thank you for introducing yourself and coming to our g2g forum to ask a question and your ancestors. You picked a great place to ask a question and I am sure that one of our wonderful genealogists will find you an answer.
As an alternative, you could upgrade to a Family Member, put Ellerbrock as a tag, and you will immediately find 327 ELLERBROCKs. Related surnames: ELLERBROEK (47) ELLERBECK (51) ELLERBROOK (7) ELLERBRUCH (2), already on WikiTree.
Good luck with your search.