I\'m currently revisiting an area of my Windows-based software and looking at changing the relationship from 1->M to M->M. As a result, I need to adjust the UI to accommodate se
A search feature that filters records in real time as you type would probably be a good idea to include. Another would be the possibility to sort the records.
Since there may be a lot of records, the best choice in this case is probably to have a separate area which displays what you have already chosen, so that the user won't have to scroll around the selection areas to find what they already have.