Sangam,
In Aras, the relationship between two items is itself an item. For instance, a part is an item, a document is an item, and the relationship between a part and a document is called a Part Document item.
Since the Part Document itemtype is ultimately like any other itemtype, you can add whatever properties to it that you want. As an admin, open Itemtypes, search for your relationship (I'm going to keep using Part Document as an example) and hit edit. You should now be able to add properties by adding rows in the properties tab. All new examples of that relationship will have the property field you created, though you may want to add information to that relationship via some automatic method.
Skyler C.
