There was a wtchtower October 15 2007 ph 10 onwards Responding to your conscience. paragraph 14 says not to judge.
Question from readers 2002 15th of May Would it be advisable for true christian to attend Wedding or Funeral in a church. Can attend as observer.
Both articles are weighted towards not going and are taken if you have a wordly husband who wants you to attend etc. there is some wriggle room but if he is keen not to go he will use it as justification.
The way I would approach it is that this is a fine opportunity to demonstrate shared humanity, by attending the funeral then anything they write in the condolance card will carry more weight and the parents would later be in a more receptive mood to listen to the message. What is their main priority here, to alienate others from the truth or to show their love and sympathy at a difficult time for the family. We talk alot about how people's circumstances change and they become more receptive to the truth, however it is also true that these life changing events can have long lasting impact if handled incorrectly. By being stiff necked we could actually be stumbling them. This is a conscience matter and when this is the case we need to think of others not of ourselves.