In your case, I simply would NOT allow them access to my children. You do not tell a child they aren't smart enough and need to collect a check or give food that's not welcomed to someone else's infant.
I'm particularly peeved at the get a check comment. Personally, I'd have been on her door step telling her not to come near my child until she works out her obvious issues.
No adult tells my child they aren't smart enough etc and doesn't evoke an extremely angry mama bear response from me.
"You think that true love is the only thing that can crush your heart;
that will take your life and light it up or destroy it.
Then, you become a mother."