Thank you for the continued guidance :-)  If I understood correctly, I could indeed define a method on the m2m to update its dataset (so we could have the filter there).   However, in any case, is there a reference to the parent m2m I'm allowed to use from the child m2o that's performing the request?  Or should I look into having the parent push data to the child?  If it doesn't make any sense, maybe we could chat?