Update: All is well. I spoke with a third agent and told him to swap out the first 2 flights for the 1 Iberia flight. I didn't even bring up if it was allowed or not (my mistake the first time) and he did it without much trouble. The change also bumps us down from zone 6 to zone 5 so we each save 15K miles in the process.

All booked!

Thanks again for your help!