Sorry, the advice given above is not my experience. My kid's dad suddenly decided my two family members were not to be trusted picking the children up (just once a week or on occasion at other points through the year), it was definitely to try and make my life harder and have control in some way. This follows five years of having my family having our child once a week, every week, and both family members having them for sleepovers etc.
School did not want to be stuck in the middle. If I changed the list of who could collect they would notify him, and vice versa. After a few times of it being changed (he took them off, told me they could be put back on, then took them off when I didn't agree to his latest demands) the school asked for a meeting with both of us as they were worried a mistake would be made and we both have PR.
Dad refused the meeting. Therefore school said until an agreement could be made that only me and dad could pick up.
I understood schools point of view, they were messed around a lot. But it meant my life became harder, my kid had to go to afterschool club which they hate, and my controlling ex continued to have that over me.
I'm in court in the next few months and I am hoping I can have it in the court order that these family members will go back on the list as there is no reason for them not to be besides his random allegations where there is no evidence. I mainly need it when taking one child to medical appts then the other child needs picked up.
However, if it helps I did work around it by using family members to do drop off to school, no one can stop that. It helped a little!