On a few forms we use in CRM, we have look-ups to relate entity records. Prior to UCI, that look-up would allow for selection of multiple records.
Example: An order record that touches 100 phone numbers.
Now that we've transitioned to UCI, the new dialog to look-up a record is limited to a single selection:

Is there a way to make this a multi-select, similar to how it used to function? Having to lookup each record individually is NOT an acceptable answer, and creating an upload for this is not reasonable in most situations either.
I'm getting a lot of heat on this one, despite my user community not bringing it up during testing.