No TJ it depends on how the airline does their loadsheets. Some use the piece concept (eg. each bag weigh a certain amount) or they use the actual weight of baggage checked in.
As for people with wrong documents it will soon come back on the supervisor or rep when the Immigration officals at the point of entry refuse them.
As for checking in 35kgs bags . Its a BAA byelaw due to Health & Safety. If your gf is really worried about it she should have a quiet word with the loaders about thats going on. The lads will soon be up in arms and the supervisor will be red faced.