If you are a QSL manager, you should arrange to have the log transferred to your main login (if necessary, use the callsign transfer process - see https://clublog.org/requesttransfer.php).

You may, by consent with the owner of the log, also upload their TQ8 certificates to your account and by that route act on the owner's behalf to sign QSOs for LoTW. You will need to agree that you will have shared custody of the certificates, but this is between you and the owner of those certificates. Once you have agreed to do this, you can use the Club Log LoTW tools as usual.