I presume you are referring to grown sons and daughters, since you can easily use the words children or kids for young sons and daughters. (Use of the.
As AndrewGrimm notes, "children" has two very distinct meanings: It can refer to people who are not yet adults, or it can refer to people who are.
"Parents will find the Bouchers to be experienced guides in the art of praying for grown children. If you are wondering how to pray adult children through the ups.