You can buy something like a skuff gaurd for the front seats which fit on the back to stop kidsmarking to back of the front seats when they kick them which is what my daughter does sometimes and it stops her marking the seat.
Also on our old A2 it had a key switch in the glovebox to deactivate the front airbag if wished,,,dont know if this was an option though??.
Also as has been said a large blanket over the rear seats should help, and as an extra measure I also placed a doubled up towel under the baby seat which helped prevent the babyseat from denting the A2's seat base as we didnt ever move ours as we had a second one for my car!!.
Good Luck mate.