I have an access database that tracks parts and as part of this i need to assign these parts to a set. I have a lot of old data that I imported so I took the old data, normalized it, and model these sets with a one-to-many relationship with the one as the set and the many as the part. I have the input setup as a form with an input for the set, and a subform in datasheet view to add each part to the set. the issue I run into is when I go to assign a part to a set, the part is already assigned to set "null" and it won't allow me to reassign it to another set. how do i set it up so when i add a part to a set it removes it from the "null" set?