A couple questions -
- will you be at the park with them, then leave to get the car from the resort?
- what resort are you staying at?
- do you and she both have phones so you can communicate just where you are?
Each parking lot does have drop off and pick up (along with rideshare). I’d suggest using that area rather than handicapped parking. They are marked with signs and you can ask the CM when you come into the parking lot and at each CM you come to.
We got back from a 3 week trip to WDW 10 days ago. My daughter has a handicapped parking permit, but we often ended up in the Medical overflow lot when coming to the park , We were sometimes pretty far from the park entrance - that wasn‘t really an issue for us since she uses a wheelchair. The biggest issue was Medical overflow is regular spots and there was not space next to the van to transfer her in. That would work for you, as long as getting to you is not an issue for her (and she can find where you are parked).
At Hollywood Studio, the drop off point is in front of Medical Parking, across from the Skyliner - marked in blue on this map.
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For MK, you won’t be able to get close to the park; parking is at the Ticket & Transportation Center (TTC). She would need to use the monorail or ferry-boat to get from the park entrance to the TTC