A few members over the years have logged about their training in a chair. This guy was a wheelchair bodybuilder and this guy was a wheelchair powerlifter. Between the two of them, you should be able to cobble together some useful info.
5/3/1 is one way, sure, or you could consider something with more frequency like:
Mon: Vertical push/pull, moderate-heavy, 4-8 rep range
Tues: Horizontal push/pull light-moderate, 8-12 rep range
Thurs: Vertical push/pull, light-moderate, 8-12 rep range
Fri: Horizontal push/pull, moderate-heavy, 4-8 rep range
So basically: Shoulders (pressing), back (pulldowns), bis or tris; chest, back (rows), bis or tris; shoulders (lateral variations), back (pulldown variations), bis or tris; chest, back (row variations), bis or tris.
I will suggest 2 x cardio sessions a week of 20-30 mins HIIT on the arm-cycling machine on non-lifting days.
Remember that intervals on a hand bike could be as easy as X time forward, Y time backwards. Doesn’t just have to be alternating slow and fast.
Instead of separate cardio sessions, you could tack on 10-20 minutes of “whatever” after each lifting session. Maybe invest in some boxing mitts and gloves and let her hit the pads. Does your gym have battle ropes? Or medicine balls and room to throw them? Resistance bands for a circuit/complex?