I'm late to this thread but still want to send you my support momof5. I would be charging a lot more than $50 for siblings and don't offer a discount. I did it once a long time ago and it wasn't appreciated at all. The parent you are talking about won't appreciate all that you do either so in this case it's probably better to cut your ties and find a great family.

Why should you take a pay cut because the two spaces are filled by one family instead of two? Don't sell yourself short. It costs a lot to feed these little munchkins.