Hi Roxanne, and welcome to WikiTree. Thank you for introducing yourself in our g2g forum. It is so easy to upgrade to a family membership, and the best part is - it is free. Once you become a family member, you can add Voigt and Zeier as tags. You will be able to access all of the people that are researching those two names, which should give you a better change at finding your great grandmother.
Good luck in your research, and once again, welcome to WikiTree.