My granmother was Ana Wellenberger, (its not Yellenberger). They married the Hammer family in Lacarak, a large family. Ana recently passed away, sister to Elizabeth and 5 others. They all grew up in Lacarak on the Sava River, just west of Mitrovica. I have the same family tree as you, and my father grew up there (still living) and he lived there too (prior to Oct 1944 when the family fled from the Russians during WWII - chased out by the Serbs and evacuated by the German army into Austria). Half of our family were never seen again, and I have many details.
I am looking for mothers/fathers of Maria Reis, Jacob Wellenberger, Elizabeth Rack and the Hammers - and have a stack of info on my own research.
I hope you get this email soon.
Cheers