The overlapping generation is easy:
2 centenarians overlapping by 20 years each*, reads
2x 100 = 200 - (2x20) = 160 + 1914 = 2074
+1 Year to sort out Armageddon = 2075. wich is
the anniversary for another of wt's already proven false prophecies
because it can not possibly be the partakers, overlapping or not.
* assuming that the under lapper was 20 year old in 1914.