I don't even know if this is possible or not.

I have a form that I have copied, one is to view a specific record from a list on another form and the other is a record viewer that admin can use to click through all the records. Since I copied it all the controls are the same. From either one of these forms there is a command button to add a comment to that specific record. when the input form comes up I have a unique record number field that references the form in the default property by using: =[Forms]![frmProjects]![Reference Number] and this works fine, however when I use the other record viewer and I try to add a comment this default does not work. I guess my question is this: can I make an IIf statement or and Or statement or make some code for this defailt text box field that woud go something like this

=[Forms]![frmProjects]![Reference Number]Or[Forms]![frmProjectsViewer]![Reference Number]

Or possibly: if =[Forms]![frmProjects]![Reference Number]is current or open then use this if not use [Forms]![frmProjectsViewer]![Reference Number]

Grasping at straws here.
Thanks, Joe