Can my sibling claim our father’s unclaimed funds and not have to split it with me?

I keep getting calls from a woman claiming she's from a business who finds unclaimed funds. My father passed a year ago with no will. I also have a sibling and we don't speak. I've researched this company. The address they give is a PO box at a store. They won't give me information unless I give consent, won't send paperwork saying it's done over the phone. My sibling has given them a lot of information and I suspect scam and will not. If it is legitimate, can he claim all the unclaimed funds for himself?