Signing custom UTXO

Hi guys,
two years ago I set up BTCPay with xPub from my Trezor accounts. Mostly we get LN tx, so that is ok, but we got two on-chain and I am not able to access the funds, the xpub on BTCPay does not correspond to any in my BTC accounts. Maybe I forgot something, but I do not have any other wallets, so I have no other way to get xpub. On FB they suggested that the derivation scheme of BTCPay changed this.

So my question is, given I am quite sure what account it was generated by, I have the UTXO’s that should belong to that account, can I add them to Trezor to spend them or not? Currenly those UTXO’s do not appear in my Trezor.

I have been looking online, but cannot find if this is possible. Can you help me, please? The amount is not very large, but still I would like to be able to access it.

Thanks a lot and happy new year!