Originally Posted by fassy

Hmm, not sure. Since you can drop the the out- or inbound leg from a ticket and it gets repriced from a return to a one-way it should also work the other way around as long as there is award space open on one or the other end. Assuming you have a ticket for

#1 CPH-EWR 9/6
#2 EWR-CPH 9/10

and want to merge them and get it repriced to a return, take a look if there is award space on either 9/6 or 9/10. Assuming there is an open seat on CPH-EWR 9/6, call in and have them change the EWR-CPH ticket #2 by adding the CPH-EWR flight and have them ticket the change. Insist on getting the new e-ticket! then cancel the original ticket #1 . Or the other way around if there is free award space on 9/10.

Haven't tried. But I see no reason why it should not work. Repricing awards tickets after a change, even by adding or removing legs or changing class of service always worked for me.

The only thing which definitely doesn't work is merging the two existing one-way tickets and get it repriced into a return flight.