Recently in fun #genealogy mysteries, I'm researching my wife's GGM Rose, b. 1901 in a small US town. She had a brother Frank, b. ~1894 in Italy. He's with them on the 1900 and 1910 censuses, but then he disappears. He's included in obits for his mother (d. 1944) and brother (d. 1947). We haven't found his birth record yet.
The mystery? We recently got their mom's will (1933). She names all her children, some to mention they already got theirs so they get $1. She doesn't mention Frank AT ALL.