This sounds like it should be possible since the two can be joined by the user, but I don't have any user allocation data in my instance so I can't verify this. Create a relationship from the module on the left nav. The Name will be whatever you want to appear on the tab. Applies to table = interaction. Queries from table = user allocation. The Query with script will look like this:
(function refineQuery(current, parent) {
current.addQuery('user', parent.opened_for);
})(current, parent);
Now you can right-click the gray header bar of the interaction record, then Configure -> Related Lists and select the one you just created.
