Relation Manager + Repeater?

I am using a relation manager to display daily payroll entries. When editing such an entry, I would like to be able to display all of its associated 'service members' who were active on that day, via a BelongsToMany relationship. Unfortunately, it doesn't seem that the form is adding new entries on save, despite the database being updated. Am I doing this incorrectly? SS1: First look SS2: Adding a new SM SS3: After saving (Code in thread)