I think I need to use the relational table because the check boxes that contain the ID value are in a repeat selection, plus they need to pre-select when the form loads.
My main table is manuals
My option table is chapters
My relational table is map_mc
It's funny - the preselect portion works fine (the form loads with the current relational table data pre-selected), but when I submit my form the relational table behaviour just deletes the records with the main table ID (MANUAL_ID) rather than updating/adding them. It makes me the form is not passing along the option table id (CHAP_ID) and may have something to do with the way I have my checkbox values set up, but I'm stuck.