As Nick say’s, If she needs to access the boot to pull out a wheel chair then i’m not sure any tow bar mounted rack will do. My brother has an Atera and although it slides out away from the car on a sort of curved rail, rather than just tilting it doesn’t give unfettered access to the boot, not enough to man-handle a wheelchair out of. You’ll be stood to one side and have to lift it out at an angle, then lift it high to turn and clear the rack and bikes if bikes are on the rack.
One option is the Thule Easyfold. You can get a 3-bike version and when the bikes are off the rack the rack folds in two so you might be able to access half the boot to get the wheelchair in and out.
The only other option if a roof racks are out is a tow bar rack that can take the bikes and the wheelchair, if you don’t mind the wheel chair not being in the boot, maybe the Thule Easybase with some attachments – you can get bike attachments for it but not sure if there is anything for the wheelchair?
The best option is probably the Thule ClipOnHigh tailgate mounted rack which clips onto the tailgate and means you can open the tailgate with bikes on BUT they only seem to do a 2 bike version of that and the tailgate won’t stay open on its own with the bikes loaded – it would have to be held open. They do a similar 3-bike version but does’t look like its intended to be opened with bikes loaded, but tailgate can be opened with the rack mounted, so bikes would have to come off to open the tailgate to get the wheelchair out but you’d have full unfettered access.
that’s the catch with these things. There is always a compromise to be made, you just need to decide where you are prepared to make the compromise.