How populate form field with an option for a popup form

I have a form and the user can create a new record from the navigation bar at the bottom of the form.  There is no command button to add a new record.  When the user clicks the add record button (on the navigation bar at the bottom of the form) I want a form to popup that has three choices for the user to select from.  This form will have three option buttons... (M)anufacturing, (P)roposal, and (I)nstallation.  When the user has selected one of the three choices I need the first form to have a field populated with either a "M", "P", or "I" (from the form that popped up).  The name of the field on the first form is "txtDrawingType"   The name of the 1st form is "frmDrawings" and the name of the 2nd form is "frmTypeSelection".

There is a 2nd part to this question but since we are to ask only one question per topic, I will save it until this one has been resolved.

--Steve