"Their children eat breakfast."
Translation:הילדים שלהן אוכלים ארוחת בוקר.
I don't understamd your question, but if it is what a group of both women and men called, the answer is that you always pretend it's males.
A boy and a girl that are friends: חברים.
A group of boys and girls: ילדים.
A group of different sex dogs: כלבים.
The pronouns have the same rule