This module is great!!. Good job.
I am however experiencing one problem. I have a dataobject "PageBanner" where it $belongs_many_many to a Page and a Page has a $many_many relationship to the "PageBanner". I have added $many_many_extraField on Page.php to add a Sort column to the many_many relationship.
So if I use the GridFieldManyRelationHandler and click "Change relation status" I can easily add the same PageBanner to multiple pages. On these different pages I can then change the sort order, so the banner is in the correct order on the different pages.
Now when I click "Change relation status" on a new page I am shown two versions of the PageBanner. It is appearing twice because the sort value on the many_many table is different.
Do you know of this problem and have ideas on how to fix?