Entity Framework 4, hybrid relationship implementation

Question

We have application where there is a layer between entities which provides relationship.

Chair -> RelationTable -> Legs

(In Chair)So Chair id # 1234

(In RelationTable)In RelationTable 1234 -> 1, 1234 -> 2, 1234 -> 4

(In Legs)Leg id #1, Leg id #2, Leg id # 4

• Now i am looking into implementing EF4 as they have POCO.
• Is it possible to define custom relationship logic in EF4? So i can create custom query part for relationtable.
• It may look like i can use relationtable as just another entity but it's not that simple it can get really complex and i need to make it transparent.
• I want RelationTable to be as foreignkey relationship form EF.

Custom behavior - One example of custom behavior is depending upon time of the day i have different data mapped from parent to child.