I am a Nanny who has been working via word of mouth for a decade.

If I do not match well w/a specific family, then I do not.

I am sure families all understand how important compatibility is in this line of work and it is expected that not all matches will be a great or even a good fit.

As long as the Nanny does not badmouth her employer to me or anyone else than what happens with her and another employer will not affect our relationship.