along with Eric's idea have you incorporated the one and a two and a three and a four concept(at all tempo speeds)?realizing this is chord territory basically it also is huge in melody and arpeggios in the form of fretboard logic.another winning concept she should try.we really do want to help.assuming you know your fretboard logic would it be a big deal to pass some along to her?generally speaking adults are not the problem.being able to comprehend and remember what has been learned might be.enter mastering the fretboard.once this is done it really is hard to mess up. her being able to progress on her own should follow suit shortly after the above has been done.just thoughts
from someone who has played by ear over four decades and still going strong.like her played classical piano many moons ago but for some odd reason the theory part of it stuck when guitar became my focal point.a lot of ''theory'' is overrated and not an absolute to learning the instrument.too many greats to name that never give theory a second thought.they just do like The Who song.''pick up my guitar and play just like yesterday''
additionally she must learn timing because just rhythm without time will get her nowhere fast.melody as in singing helps but playing by yourself/herself she needs the challenge to better herself.consider being her backing track in a lesson.ask her to play along hoping she will fill in the gaps.
yes,tall order but one actually necessary as much as the above mentioned.
after all it is called ''playing'' guitar for a reason Not working guitar.
We hope this provides a little insight.aka inspiration she needs.