Just to be absolutely clear: anytime there is a re-issue, a re-issue fee applies. In the situation you describe above, no re-issue fee applies because there is no-reissue, not because there's a situation where a re-issue occurs but with a waiver of the fee.

The TA may not be totally familiar with the situation where a segment on the reservation is changed to another carrier, but the ticket is left on the original carrier. Because of the fare rules on the *ONE* tickets, the new carrier can lift the coupon of the original carrier's segment at the time of the flight, whether it be paper or electronic.

This situation may be made worse if your friend is asking the TA to "change the ticket," as this may subtlety be leading the TA down the wrong path. They want the reservation changed to reflect the new carrier, but leave the ticket as it is. Whether the TA chooses to charge a fee to change the reservation is another matter, and is outside the scope of the *OWE* fare rules, but that would have nothing to do with a re-issue or re-issue fee.