But if actually, someone did help you to create a bitcoin wallet, then I advice you never to use that wallet, learn how to create one yourself, and only use wallets you created yourself, never trust your wallet keys or seed phrase with any third party, be it your brother or sister.
It is assume that this wallet belongs to two persons and the people I think can share the same wallets are couple that marriage has brought them to become one, and this can only take place based on agreement from the person. If it is something that has nothing to do with marriage I think it is not right for people to think of sharing wallet or someone helping a someone else to create a wall. Wallet is person and it is very important people should learn to keep its information private.