When children are regularly in ongoing mixed age groups, the staff-to-children ratio and group size applicable to the youngest child in the group shall apply to the entire group.

This goes on to have exceptions to this rules in section O.1 and O.2.

It might be less confusing to say:

When children are regularly in ongoing mixed age groups, the staff-to-children ratio and group size applicable to the youngest child in the group shall apply to the entire group except in the case of a balanced mixed age group as indicated in sections O and P.

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