What we speak has power as Christians.   We have power to speak life and death.  

“The tongue has the power of life and death, and those who love it will eat its fruit.”  Proverbs 18:21

And as parents, we have relational authority over our Children.      Speak what God claims for your children.

My child has the mind of Christ (1 Cor 2:16).  My child can do all things thru Christ who strengthens them (Phil 4:13), and My child will be blessed and not cursed (Deut 11:26).