Hi Amara -
Welcome to My Swiss Alps.
You will be traveling at the very end of the Summer season, and the beginning of the "low season" that starts on about October 15th to 23rd. Skiing picks up a around December 15th.
While you are there, most of the tourist services in the high Alps will be available.
For general information about where to go and traveling in Switzerland, this My Swiss Alps website has a lot of information for first time travelers. Please start on the home page and follow the links under the different headings. You'll learn a lot to help answer your questions in general.
Specifically, for 8 days, and with travel perhaps a bit of a burden, I'd choose one or two locations as bases, and explore near them, and take day trips by train.
For planning and carrying out all your travels, the SBB timetable is invaluable. Please make sure to read the comments and explanations on the first page of this link:
Luzern is a good place for all kinds of scenery and day trips:
I'm uncertain about the Bernese Oberland/Jungfrau regions, because I'm not sure how well the small trains handle wheel chairs. I'm sure that they can, but i don't know the details.
Interlaken could be a base....not a very "touristic" town in its own right, but good access to the places like Grindelwald and Lauterbrunnen.
Can your daughter climb a few steps?
I'm sure that others can jump in to add to my comments.
There are special services for handicapped travelers. I don't remember all of the web sites, but a Google search will give you some leads.
Here are a few:
and, in this thread toward the end: