Welcome!
I can't tell you how scared I am even writing all this.
You may wish to ensure that your screen name is a nickname which preserves the anonymity and privacy of your children and others they may interact with. The board rules are posted in the shaded header at the top of the Forum, and include the reminder, "Try not to post any information that will allow others to identify you, your children, or anyone else."
"Is it enough to know my children are gifted or should I get them tested to see if they are highly gifted?"
Testing typically reveals relative strengths, and also relative weaknesses for which a child may be struggling to compensate. These are good things to know for raising, coaching, and encouraging kids through the years.