In 2019 we had a large group of older teens (maybe adults) with their parents in the disabilities viewing area for the Halloween parade at the MK. They were sitting at the front edge with many wheelchair/
ECV people behind them (I was along the edge a couple of people down from them). People behind them complained because they were standing in front of others who couldn't stand but CM's didn't do anything really. It was awful for the woman in the power chair next to them...I was just annoyed but they were all over her jumping up and down and what not.
No one has ever asked me about a
DAS - I use an ECV and have had no problem using those viewing areas unless they are full. I've also seen them let in about 10 family members with the person in a WC/ECV and not seen anyone make them move if the area got full. At Epcot be prepared for family members to stand up when Harmonious starts and block your view unless you are up front. I have zero problems with anyone not in a WC/ECV using that space as long as they try not to block others who are seated (just to be clear on that!).