Attach parent-chain evidence to the correct Elements PSET input
A multi-input Elements signing packet can contain both ordinary sidechain coins and a peg-in. The parent-chain transaction, proof and claim data must attach to the peg-in input specifically.
Update the intended input index
The sample assumes the second input, index one, is the peg-in. Verify the unsigned transaction layout first. Provide the actual amount, deposit transaction hex, proof for that transaction, claim script and genesis hash of the parent chain.
elements-cli updatepsbtpegin "$PSET" 1 "$VALUE" "$BTC_TX" "$PROOF" "$CLAIM_SCRIPT" "$PARENT_GENESIS"
Review the updated packet before signing
Keep the returned base64 packet and inspect the input metadata in your signing tool. A parent genesis hash for the wrong network or a proof attached to the wrong input invalidates the intended claim context. Updating metadata alone does not mature the deposit, produce signatures or submit a transaction.