AFAIK as I know you can you use that assocation in both ways without changing the owner. The OQL is transformed in a SQL statement that does a 2 step join (item to item_item table and item_item to item).
Selecting children of a parent
FROM MySecondModule.Item CHILD WHERE CHILD/MySecondModule.Item_Item = $PARENT SELECT CHILD/Name As Name
Selecting children with parent
FROM MySecondModule.Item ITEM LEFT JOIN ITEM/MySecondModule.Item_Item/MySecondModule.Item PARENT SELECT ITEM/Name AS ITEMNAME, PARENT/Name AS PARENTNAME
If you have a non-assocation reference from one entity to another (classic database foreign keys) you can make oql like.
FROM Integratie.ImportWerkorder AS IRC LEFT JOIN Contracten.Werkorder AS IR ON (IRC/Nummer = IR/Nummer)
you can trick this with an autonumber which you have to copy (sorry) to the children of the item