Item requirement form - Project ID Lookup

In Project Management and Accounting

Common - Item task- ITEM REQUIREMENTS

 While creating a new record, the first field is PROJECT ID, This by default shows all projects. Is it possible that i can filter this lookup list, based on a  Condition say  Project group  = X . Only in this form. I don't need the filtering to happen if in the user goes to Common- My Projects-- Item requirement. or Common - All Projects - Item Requirement

In a nut shell the lookup should filter only in Common - Item task- ITEM REQUIREMENTS; not anywhere else

Thanks

Thomas