We had this issue aswell, we had a locations module to build that needed to store features for a location. I am not sure if this has changed, as typically you would look to link objects, but the way we were told to do it was via a tracked list of GUIDs, so in out LocationItem object we had:
this allowed us to track the services (ServiceItem is another object in the model) linked to the LocationItem.
if(this.services == null)
this.services = new TrackedList<
var pc = this.Services;
foreach(var id in value)
In the fluent mapping, i dont think there was anything special
locationMapping.HasAssociation(p => p.Services);
thats all i could see, and it has been a while so i dont think there is anything else.
Hope that helps a bit.