Thank you sooo much!!! This clever little trick worked, im super impressed and thankful that you managed to figure that out.Regarding seat selection, I had similar issues recently that I finally got sorted by using MMB on various OW airline websites. I usually find RJ is the most reliable site followed by MH.
If you can only select for yourself - as was my experience - log in to RJ using your SO's surname and only select their seat for one flight and then exit. Repeat for other flights. That should allow their seat selection to be made. Then do the same for your seats - using your surname of course.
It mightn't be necessary to do it one flight at a time but I did it that way to be sure and it worked.
As a side note, I had some IB flights in our itinerary that I couldn't make any selections for - even using RJ. The seat maps wouldn't even load. I managed to get this sorted by using CX - which only allows you to select Window or Aisle. But what that does is actually give you seemingly randomly allocated seats which you can then change on RJ.
The things you learn!
The first method worked for the JFK-MAD flight.
Second one with CX worked for the MAD-FCO one but it wouldnt let me edit with the 2nd passengers logins on RJ. I had to randomise it on CX until we got a seat we liked and then edited mine on RJ to the seat next to hers.