If i can understand it right you need to check if there are
any files uploaded aleady. If there is let user only upload the
file that's missing. So if in your upload form you have 3 separete
file selections, so lets say user has already uploaded 1 file and
it's in Attachm1, hide this item in your form.
<cfif query.Attachm1 NEQ "">
"Hide File Selection for File 1"
<cfelse>
"Show File Selection for File 1"
</cfif>