Your kids may have become convinced that they need to be baptized to assure their survival at Armageddon.
If so, this is proof of their SPIRITUAL IMMATURITY and lack of "accurate knowledge."
Throughout the years, the WTB&TS has made it clear that minor children will benefit from the faith of their parents.
Since both you and your wife are JWs in good standing, it is entirely appropriate that your MINOR, DEPENDANT children not be forced into a decision they are not mature enough to make.
You would not let your kids get married at this age, and Bethel would not consider them as volunteers at this age.
They might also be "too young" to be full-time pioneers, but I'm not certain of that.
You can make a big, JUSTIFIED stink about how you will not tolerate having your children question your "god given" authority.
In this instance, you may be of more help to them by not leaving so soon. you can protect your kids better by using your headship to shield them from harmful WTB&TS radiation.