Otto Mueller, born Germany married Bertha Borth born in America. They had daughter Heine B. B. Mueller who was born in Wausau, WI on 14 Jul 1902.
There were other Otto Mueller's born in Germany, in 1856, 1881, 1906 and so on.
Would you have a year of birth for your paternal grandfather and what country he married in, and what year he married?