If I have a join shared wallet and my partner lost the backup, can we recover this if i can i see the BTC yet?
Assuming this is a 2-of-2 multisig shared wallet, it is not possible to do anything with the coins without signatures from both wallets.  Bitcoin uses strong crytography, and when signatures are required, they're really, really required.  That's why it's secure.

If your partner has irretrievably lost the wallet and backup phrase, then the two of you have irretrievably lost the coins.  Sure, you can see them, but you'll never be able to spend or transfer them.

Sorry.