Extended keys and signing TX
Question - To spend the funds how do I sign them I mean do I sign them using the TPriv key or I need to derive a private key from the TPriv key ?


To spend the UTXO of a child address (derived from either your xpub or xpriv), you will need to use the xpriv key to derive the child private key that is related to that address. The child private key will be used to sign the transaction, the parent private key cannot sign for child UTXOs (with or without the chaincode).