I know there is an area for wheelchairs on the drill hall floor, one family member can sit with there too, the rest sit up in the bleachers.
The Navy Lodge has ADA rooms, but I think you need to call them directly to reserve those. Not sure.
I am in a wheelchair and went to my daughter's PIR in August. No problems with accessibility. Section for wheelchairs and one family member on floor others sat directly behind on bleachers. Navy lodge has accessible rooms. Go to Sarges meet and greet, let him know and he will reserve a spot that is easy with a wheelchair.
Sarge's M&G is the evening before your PIR.