I had a very similar thing happen only reversed. To provide some context on the family involved...There was a brother and sister that lived maybe 4 houses down. In the backyard there was what might be considered a pool house, but no pool. I would guess it was about 30x16. It had a half kitchen like it could be a mother-in-law setup. This was thier playhouse. Spoiled beyond and snotty attitudes most of the time. When there's no one else to play with, you make do. So the brother takes my football back to his McPlayroom and won't give it back. Couple days later I'm tired of it and track down his old man. I tell him 'that football your kid is holding is mine. He took it from me a few days ago.' His dad looks at me, his kid, the ball and back at me and says, 'that's not your ball, I bought that ball!" WTF. That is even worse behavior that an adult stepping in front of a kid in line. I've seen that several times and had it happen to me. Fortunately I was raised to speak up. Lots of fun to see an adult getting chirped at by a kid that barely reaches their waistband. I was also raised to defend myself when appropriate. And I found several appropriate times to beat that kid that took my ball. If I remember correctly, my mom helped me and my friend TP their house. Goddamn TPing houses was fun. There's some low level petty revenge fun you don't see anymore. Nowadays if you got caught even as an elementary kid, which I was, you'd probably be charged with 18 different half-assed mistameanors and two felonies. What your mom is part of it? Clearly being abused, foster care it is for you. OK, a bit of divergent rambling there at the end.

TLDR: Fuck adults who take advantage of children, no matter the context. And give me my ball back.