I'm just asking out of curiosity really.

Basically, when FDH and BM had this court order arranged SS(4) was 1 or 2 years old.
The CO stated that FDH picks his son up Friday 9am and brings him back Sunday 5pm. Its different now because SS is now in full time education so FDH picks son after school (though i'm surprised BM doesnt tell FDH that he has to take son to school)
The reason i'm asking really is because my FDH works nights but what if his shifts were changed to the day and he wouldn't be able to pick his son at 3pm. Does FDH have a right to ask BM to pick their son up from school instead and he would get him after work? Knowing full well that if this happened BM would kick up a fuss and threaten FDH with not seeing his son again because according to her, picking up his son is more important than working (really its just coz she doesnt want to get off her lazy ass) and what if he's working on a Sunday and can't bring his son back at 5pm, could she not come get him? Can she legally stop FDH from seeing his son because of these circumstances?
This is something that may not happen for a long time but i know it will happen one day, can she really take control of his working hours?

Just to add, i have a son of my own that i pick up from school myself (different school to SS) so i can't pick SS up from school and i wont drop him home on a Sunday because when SS leaves on a Sunday it's the only time over the weekend when me and my son get to spend some real, quiet, quality time in the house together.