There is no such thing as married segments for upgrades-- it is just a glitch of how R availability is displayed.
Try buying the ticket you want (you can always cancel it within 24 hours). Go to request the upgrade and see what happens. It should show available.
You are 100% correct thanks. It doesn't show up when they are married, but when it is actually upgraded it is segment by segment. All booked, ticketed and ready to go.
I have all R now except the BKK to/from, which I knew.