NO the rule is per premise so all floors count as the same premise. Also remember if the friend leaves for any reason they must take their own children with them or they would become part of your group of 5 and put you over in numbers. They can only be at the daycare if their parent is with them.

There are no two caregiver more kids allowed in Ontario.

If only one of you has kids and holds the daycare at the home of the one with kids then you could have 5 more children and both of you work the daycare and that would be a selling point to parents in some cases but figure of the 5 kids that one goes to pay for the house expenses and teh other four are split so your income will be the fees from two children and your friend will get the income from two children. Most providers can not make a viable profession out of daycare with only having two kids in care.

Also I am assuming you are planning to do it at the home of one of you. If you were looking to buy a separate home for the daycare then you would no longer be a home daycare and would need the new home zoned as a daycare centre and come under DNA rules.