Testing transactions between external wallet and vault wallet in sandbox?

I want to try transaction from/to an external wallet from a vault wallet, is this possible in the sandbox environment?

If the external wallet is a Fireblocks vault address in the same workspace.
You should be able to create a transaction.
Please note you can only create transactions when the source is specified as a VAULT_ACCOUNT

Thanks for the reply.
But what I meant with external was a none fireblocks wallet. Transactions between fireblocks wallets ive tried and its working great, but I would like to try the usecase of a wallet outside of fireblocks in the sandbox.

But I guess that is not possible considering the test blockchains that are being used etc?