is it possible to control what relationship contacts are used for the actions?

I have a rule created in CiviRules that triggers on the creation of a relationship and creates an activity. I'm finding that the activity creation will create two records -- one for each of the two contacts defined by the relationship.

Is there any way (including via hooks) to control the action parameters? I want to specify which of the two relationship contacts should have the activity attached.

Ideally, I'd also like to control who is assigned the activity dynamically (i.e. via one of the relationship contacts).