inserting new messages into a read message?

Hey everyone, this seems obvious but i can't fathom it - I want to be able to send a set of text (file names or numbers) into a read message but have the 'read' part of the message stay and just change the file name or info after it... I can't compile a umenu list as the idea is that people type in the name themselves and don't have to work about typing 'read' at first - so it's more automatic and easy for an audience to use - they will be doing it over the net too..... such a simple problem but it's totally foxed me!
Many thanks for any ideas.