If you could send me, to my e-mail address, details of birth, death, marriage years and places, plus ages at death, and spouses' names I will check my records for you.
I gather that a Donald U'Ren fathered both Donald junior and Bill?
I do not have extensive records for events outside Australia, except where the CWGC and 1st AIF are concerned, plus the 1881 Census and other resources on line.
If any of the family died or married in NSW after 1945, I cannot locate a death record for you, as these indexes are not in the public domain.Other sources may help though.
The BDM records of our States vary considerably in date range, content, format (which can seriously limit searches) and assorted other issues.The certificates, too, vary a lot, depending on the time period and State/Colony.
Have you checked the Eng/Wales GRO Indexes to Army deaths, if Donald senior did not die in WW1 or WW2, and of course if he did?This is in addition to the CWGC Site, which should be your first port of call if you are on-line.
If you can't access the resources I've referred to, please let me know where you are located (the nation and whether in a major city or out in the sticks), and I'll see what else I can recommend.