Upvote:2
Assuming by "China Air" you mean Air China the mainland airline (rather than China Airlines the Taiwan carrier), I had no problem booking it on Orbitz with a few extra clicks. Kind of expensive though ($10K) vs. $5K-ish on China Air return (both for business class).
Upvote:3
Simply ask the Delta agent to book you a paid ticket on the same flights. They can tie the two reservations together, so any airline imposed changes apply to both bookings.