Interesting that you mention John's nice and talkative son. That would be uncle Jack Tjepkes who does live near Minneapolis and did go to the birthday. If you are referring to Henrietta Donaldson, sister of John Tjepkes of Thermopolis, Wyoming, I happen to posses one of her scrapbooks with mostly newspaper articles, no pictures.
It would sure help me if you knew the names of Martin Tjepkes siblings and parents. Grandpa John couldn't remember them when I last spoke to him in 1994.