I've seen some older posts about this, but would be interested if anyone has recent experience when adding a third child to a nanny share. We currently have a two-family, two-child nanny share. Our nanny, who is wonderful, cares for our two year old, and another family's two year old. We hope to add our 5 month old to the share in the next month or so, which means the nanny will be caring for three children--two toddlers and an infant--from two families.

I'm curious what additional pay is typical for adding a child in these circumstances. I've seen estimates anywhere from $1 to $5, but that's a large variation.

Also, we obviously would pay the full additional amount for adding the third child (since it's our kid), but does the other family pay a reduced share of the overall hourly rate? For example, the families currently split the cost of the nanny equally, $13 per family for a total of $26 per hour. If we increased the nanny's pay by $4 for the third child, would the other family continue to pay what they have paid ($13) and we would pay the remainder ($13+$4=$17 in this example)? Or would the other family pay a reduced amount (i.e., $12) and we pay a larger portion (i.e., $14+$4=$18)?