I'm pretty sure that ratio and licensing laws change from province to province. So it would depend on where the original pp is from .
I know in Ontario you are allowed 5 kids with only 2 under 2 if unlicensed this includes your own till age 6. But once your child is age 4 and enrolled in school you may add a 6 child as long as you now only have 1 under 2. This only apply for the school year Sept to June you must go back to counting your child in your numbers during summer holidays but not christmas or March break.
You can have a 6 kids if licence through an agency.