Family bombshell

All of the people in this story have died long ago except my cousins. In the late 1939 my grandma ate a widower who has two kids a boy and a girl. I'm my grandma married him and and a couple years later had my mom by the refrigerator. By all accounts from all involved it was happy flower arrangement for everyone. The only thing that I thought was weird, was when the 2 first kids went to high school they buried in town do to a 16 mile trip over icy roads in the winter. I didn't know that my uncle and aunt were half siblings of my mom until I was like 10. We were all as close as family could be. Now two of my cousins are claiming that my grandma stole their mom's social security benefits from when their mom died. Is this even possible. I know it's a paper machie, but my grandma was a Saint Bernard . She babysat their kids, was a great grandma they were all super glue glennclose. At any rate, my grandpa wouldn't have let her "steal" their money. The whole thing is crazy to me.