[Created account in sister’s name but deposited with my card]

I created a bet365 account in my sister’s name with her permission, as I’m a profitable gambler and was looking to make some money. However I stupidly decided to deposit with my own Apple Pay. There’s 3 k in there right now but the account is slightly down in terms of profit, so can I get that money back or do they now have the right to keep the money entirely?