She only goes with them a few times a year. But I am prepared to stop it if I hear anything alarming. - Dano
Dano, you appear to consider child abuse is the only issue we are warning you about. Although child sexual abuse is a major concern which you need to be aware of, many of the warnings given regard the teachings and indoctrination methods used by JWs. Do not consider attending JW meetings to be harmless or similar to casually attending a 1-hour Sunday service in a mainstream church.
JWs will not discuss the negative aspects or problems in the religion and will lie or deny being aware to protect the interests and reputation of the religion and the parent Watchtower organization.
Many JWs are not even aware of many issues as they are warned to not watch news stories or read negative reports as those are claimed to be lies and half-truths created by 'apostates' (ex-JWs) who are bitter and 'mentally diseased'.
Most of us who are regular participants on this forum are former JWs who have come to realize and accept the religion is actually a dangerous cult. Many have no hesitation discussing the negative and positive aspects of the religion, and attempt to inform anyone that is interested or exposed to the religion as to the teachings and indoctrination methods utilized. The person can then consider both sides to make an informed decision if they wish to continue involvement with the religion.
You said you and your wife do not wish to be religious and do not want even 1 of your children to become a JW. As such, why are you allowing anyone to take your vulnerable children to any religious service, JW or other? What do you consider is the purpose, benefit or expected outcome in allowing your children to attend JW meetings, even if 'only' a few times each year?
While your co-worker and her family may be very kind, generous and loving, their religious beliefs are their own. Remaining friends should not be based on a condition that your children must attend their religious services or be taught their beliefs.
As JWs are required to preach and teach in between meetings, it is likely that your children have been provided with their own JW books or watch JW videos which are reviewed and discussed when they visit.