How do you say no?

Official license arrived in the mail today... and first call for placement came as well.  Two little boys in a neighboring county.  I really wanted to say yes, but logistically it isn't an option.  With little ones there are as many as 3 visits a week and then there are doctor visits and court, and we just can't miss that much work.  It really shakes your world to realize how much in demand foster parents are when you get your first call the day your license arrives.