Blueridge makes a tenor and if it is anything like their other instruments it will be a fine intro to tenor guitar. And it will likely be all the guitar she will ever need.

Having learned to play 6 string guitar three times now I have deloped a few observations. The first time I took up guitar it was a 1950's Gibson tenor. In 1969 absolutely no one had a clue what it was, neither fish nor foul. The reference work wasn't easily found in a part of the US that was of a 6 string or no string mind. In hind sight I know what I needed to do to play it but back then tenors were only seen on the covers of the Kingston TRio LPs.

I learned 6 string instead which was fun and I got real good at it.

The second time I learned was following rehab on a wrist injury to my right hand. I crushed my wrist and hand in some machinery. I had to learn to strum and finger pick again. Try playing a guitar with a potato and you will have the idea. 6 or tenor would have made no difference until a year and a half of surgeries and rehab were over.
I still don't frail well.

The third time followed a table saw injury that involved reattachments and a year and a half of surger and rehab. I tried the tenor again. The span of the chords was too great for my fingers to reach for many chords in the traditional tenor tunings. Tuned like the top four of a guitar dgbe wasn't easier. Tuned like a banjo in G tuning with out the drone was much better. (DGBD I still recommend this style for the tenor.

In hindsight here if I had a brain I'd have learne to play left handed. I am a singer, not a guitar god and strumming and simple finger picking suits me well. Being able to move up the neck, something I still can't do well after 20 years, is more desireble to me and my style of play than being able to pick with 2, 3, or more fingers.

I think in this instance it isn't the missing fingers that will cause the anxiety but the missing thumb. That would be the critical issue as I see it. In my case my thumb was severally damaged but not removed.

In any case good luck with this project. Having lived through this problem my support is with the musician.

Don