I want to create links between objects (says some circles) so that when I move my objects , the links between them follows .(architecture schema)

So I used connectors to link my circles

Now I want those link/connectors to be curved, while I can curve them temporarily while manipulating the link, unfortunatly as soon as I move to another other object or link, my previous curved links returns to a straight line links :-( 

How can I created persistant curve connectors between objects ?

ascii art of what I want 

from: () --------()

           _ _ _  

         /         \

to: ()/            \()

Thanks.