How over is she? I know although yes it is illegal that a lot of caregivers at one time or another have doubled up such as with an older sibling on a PD day or started a new child a week before the old child left rather than risk losing the replacement child.

If you know the provider you could speak to her provider to provider and say that you have noticed that she appears to be over the legal limits and how that can effect her insurance and that if you have noticed the numbers others will have too including the parents she provides for and that the ministry can charge her a fine and close her daycare if they report her..... notice I worded it so that it totally appears that someone other than you would be the one reporting and that you are only warning her. Then if you do report her you might get away without her knowing or blaming you.