I read that too, but some airlines like EK has something similar to the family mileage plan too but when they will take away 75% of the miles as a 'fee', i.e. you lack 1000 miles but you have to give 5000 miles.
I saw in some reviews someone's experiencing both 50% and 100%, so I'm not really sure how this really works.
OZ hasn't mentioned a thing about it.
Thanks