Originally Posted by
Stgermainparis
Right. But shouldn’t I be able to book as multi city if they are available separately?
No, it will always try and re-validate this as a married segment. Nothing stops you from booking these as 2 separate tickets, but that has risks of course.
Have you tried calling? If you find a good agent ... could try a longsell with U-class on EI and XN class on the UA flight and see what happens