When adding a task, i want to select a meeting, and select the attendees coming to that meeting. I have a reference selector for that meeting, but cannot add another reference selector to select from attendees. I thought i will get the Attendees_meeting object from Meeting obj, but its not there.
You can only use reference selection from the entity owning the relation.
In your case
Tasks can have a reference selector for Meeting
Attendees can have a reference selector for Meeting.
I'm not totally sure what you actually want to model, but the straightforward solution seems to be: use a reference set from Meeting to Attendees, then you can use a reference set selector.