God does not have any grandchildren. God talks many times in the Bible about His children (people who had been born again). Nowhere in the entire Bible is the word grandchild mentioned.Every person who wants to go to Heaven must be born again. You cannot make that decision for anyone but yourself. That is why it is so important to win your family to Christ.
The Bible tells us to train up a child in the way he should go, maybe your children are grown and you have not won them to Christ yet. Maybe it is your parent, sibling or spouse. Never give up, pray for them, be a good example and trust the Holy Spirit to convict them.
At events many times someone, who comes into the SOS EVENTS booth to be saved, tells the soul winner that their mother, father or grandparents have been praying for them.
GOD Answers prayer. He is more interested in your family being saved then you are, so keep on trusting him for the results.
John 3:3 Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
Center for Evangelists 