Party Column in User-Defined Tabs with Linked Documents

For instance, we have created a discovery tab where we link discovery responses and documents. While we sort these by party, when we upload them directly through the user-defined tab (instead of in the documents tab), we cannot mark which party it corresponds to so when we go to the documents tab, we have a number of documents we then have to open one by one and mark the corresponding party. If we could do this step in the user-defined tab when we are marking the catergory, tag, etc., that would save an extra step and a lot of time.