appreciate the reply carmad- odd catch 22 situation.
Yes, the one-year award remaining is one thing Motability are not flexible on at all.
I did read online a while ago, that in similar circumstances to yours (early termination on vehicle unsuitability grounds), due to the Motability salesman having an unexpected day off on the day a chap originally wanted to order (and had an appointment) , the chap went back the following day and his Motability application was rejected as by that day he only had 364 days of allowance left!
Motability would not shift on the requirement for a full year of allowance despite the circumstances, so he had to ask DWP for an early reassessment of his DLA award . The outcome of which was reduced to LRM! The chap in question then had to go to a tribunal to get HRM restored and could only then order a new vehicle. But overall, I recall it took many months to resolve.
So, you are maybe stuck where you are. The option being to ask the DWP to re-assess your good lady’s claim early – but there are risks involved as above.