Finding out where those children were born in Germany is going to be the key I think in taking the tree further. I can translate the document at some time. The only real objective data for your tree is that on 1 Dec 1879 he was 39 years old. I would think though you need to concentrate on his siblings who were born in Germany. Without knowing exactly the town where they were born you basically have nothing. I am not sure how much there is online for Germany but I dont think there is a national database like they do for Holland. If you know the town where they were born you can order microfilms from the Mormoms if there isn't anything online.