I've been thinking and working on this concept for a little while now and haven't been successful. The closest remedy I could find was the the thread: " How to remove item from picklist which have been selected in previous entries in a subform context?" The user found a solution but never posted the results. I've been using the methodology that he outlined in the post as a means to get started but I haven't been successful. For reference, my code nearly mirrors the code presented in this thread.

My problem

I have a maintenance management form that allows users to mass select defective widgets via serial number. An issue that I've found is that with an abundance of serial numbers, efficiently selecting serial numbers can become problematic; not to mention that the same serial number can be selected twice.

The needed solution

I need to be to a craft a dynamic lookup that will recycle based upon the previously selected choice. (i.e., I have choices A, B, C. User selects choice A in the subform and on the next row addition the available choices are B, C). 

Please let me know if I need to provide more information for this issue. 

Thanks for any support provided, 

CM