It's not unusual to have some many to many relationships going on in my applications. In my current application, there are two grids on the form - each showing a different M->M relationship.

Last time through, I simply had a plus and a minus button next to each grid. The editor selected a record in the grid and pressed the "-" button to remove the relationship. A press of the "+" button brought up another form with a grid - from which the user could select ONE record to associate. To add a second, the user had to select "+" again.

There has GOT to be a better way to do this type of thing. The result is ugly (those +/- buttons which seem unrelated to the other controls), it allows only one selection at a time, and it's difficult for the user to comprehend. The multi-select question still lives.

Does anyone have suggestions for other methods?

TIA