This woman wanted to bring two children into the area allocated for wheelchair users, in addition to the single companion (included in her ticket price). What about the next person who wants to bring 6 family members, or 12? Would we then be seeing a "tickets shame" campaign because wheelchair users were unable to get tickets because the space has all been taken up by other users' extended families?

With the best will in the world, I do not see how any venue can provide facilities for wheelchair users which also include totally flexible provision for an unlimited number of companions.

There are a number of reasons, including fire safety, why she would not be allowed to have the children on her lap. I would be very surprised if this were allowed for able-bodied spectators so she is not being discriminated against in this respect.