There is no code there to add more than one attatchment or change the attatchment. You have to delete the record and create a new one of you need to change the attatchment right now.
Donate to UBBDev today to help aid in Operational, Server and Script Maintenance, and Development costs.
Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.