VRM4800 - Who is entitled to claim: assignment of right to payment
A person entitled to make a claim may make the claim but ask that payment be made to a third party.
You should not make a payment to a third party without authorisation in writing from the claimant – a letter of discharge – stating that payment of the claim to the third party discharges HMRC’s liability to the claimant in relation to the claim in question.
If it later turns out that the claim ought not to have been paid, you should make any recovery assessment against the claimant, not against the third party.