I'm a Nanny and have a close friend who is a childminder.I know she would never mind being asked regarding her provision of care...but then she follows the rule to the letter!
It must be hard as this is your organised care but it seems sad that you don't seem to have the relationship with your child's carer in order to simply ask her outright. Is there a problem there?
FACTS time!! Ages covered
A childminder may look after any age of child, from baby to teenager, but registration regulations only apply to care provided for children under the age of eight.
According to Government regulations, a childminder is allowed to look after six children under the age of eight (under 12 in Scotland and Northern Ireland). Of those six, no more than three should be under the age of five; of those three, no more than one should be under the age of one (exceptions are made for siblings). Any care for children over the age of eight should not be allowed to adversely affect the care provided for children under eight
I don't think attendance at school makes a jot of difference. It is their actual age.
You could say something like..."I don't mean to be a pain but I'm really worried that you may not be covered insurance wise now that you've taken on a fourth child under 5. Is everything still okay?"
One thing to note....this is children all together at the same time. She can take on as many as she likes if their times are staggered and they are never around together.
good luck
xx