In tellus' example the item would no longer be a link to the nun, since it has been changed by the ritual to be a link to something else. The desecrator, I guess, but it could be an AC to a specific demon with equal ease. Alberto might be a connection to the finger, or it might simply be a major sin of his, and the finger is an AC to a demon. or to nothing else.
Xavi
I can see the logic of having connections fade as new ones are built. So that it is usually the case that there is only one Arcane Connection at a time. There are still situations I can think of for something to be an Arcane connection to two different things though. And I do think it should only be possible to fix an item as an AC to one thing.
A knife used to kill someone could be an Arcane Connection to both the assassin and the ghost of the victim.
A saddle could be an AC to both horse and rider.
A baby should be an AC to both it's parents for a time.