Multiple Values in Rules Action?

I am using Rules & User Relationships together. I am trying to create a rule that looks like this:

CONDITION: When a user joins a group
ACTION: Create a user relationship between the user joining the group and all current members of the group

The problem I am experiencing is that rules doesn't appear to accept multiple values. In this case I have multiple values for the "Requestee" field (see the attached screenshot). I am using the rules and views integration module to render a view as a variable to display in the requestee field, however I know it is not an issue with that because even if I try to manually plug in multiple user ids into this field nothing happens (ex. 1, 2, 3 or 1 2 3). The rule works just fine if I only have one value listed in the requestee field.

I've dabbled a little bit with trying to create an action that evaluates php to accomplish this, however I am not that knowledgeable with PHP so I'm not sure what the best way to accomplish this would be in the event that I have to use custom PHP. I would think it would involve a foreach loop, but again, don't know what the appropriate code would look like here. It would be preferable if I could somehow get Rules to accept multiple values.

I've spent hours trying a variety of methods to get this to work, but haven't had any luck. I've looked all over for an existing issue, but haven't found anything that addresses this issue in either the Rules issue queue or the User Relationships issue queue. Any help that you could provide would be greatly appreciated. Thanks!