Imagine your boy and girl have been visiting your ex and his partner for 7 years. Your boy is 13 and your girl is 11.
One Sunday they return home and say there has been a bedroom readjustment. Your boy now shares with your ex's same-age step son, and your daughter now sleeps in a bedroom with a ten year old boy, that has been split down the middle with wardrobes.
How would you feel about this new arrangement?