I would like to sign a transaction from a wallet which is derived from a seed, and sign it with master seed private key, can I sign any tx of any derived wallet address after the master seed wallet?
thanks a lot.
The master private key is derived from the seed and all child private keys are derived from the master private key. Knowledge of the child private keys lets you sign transaction spending coins sent to the corresponding addresses. So yes if you have the master private key you can derive the child private keys and use those to sign any transactions related to that wallet.