Drupal 7 Rules - Set value of multiple value reference field (user reference) I have a cck content type with a multi value reference field.
Using rules, I am trying to populate these reference fields when users create a different content type (for example an event and I want to keep adding user references for people that view the event -- this is an example.)

My issue right now is that I can fetch the entity to set the user reference (using a loop of users), but I can only set the first field. 
How do I move to the next field of the fetched entity and set it to the next user in the loop list?

I imagined that as long as I was in the loop, for each item in the loop, a set data value on the reference field would move to the next field but it simply overwrites the first one.

I see that the particular reference field I'm trying to set values for is an array (fetched-entity:field-blah:0 etc). Since I cannot pick for example item [0], I thought  fetched-entity:field-blah without the delta would keep shifting to the next. It does not.

I'm thinking there is a way for me to loop through the deltas in the fetched entity as I loop through the list?

Any help appreciated.
Install next modules:

Conditional Rules 
Rules Bonus Pack 

Create a rule for "Content is viewed".
Set conditions , like "content is type"
Create a loop and set its name, in the data selector choose the field(not the deltas) like [node:field-alumnos-curso]
Create an action inside the loop(do not "set data value"), just select "add item to the list" and the value will be the list name or loop name.
Remember create a action "Save an entity".