Hi, I have had 2 children who went through your son's age. I am out of the JWs, and my parents/relatives know it. So, I am in a different situation then you becuase I had more freedom. I told/showed my relatives alot of what I disagreed with in the JWs. Perhaps some of what I did will work for you.
At first, my parents/relatives asked to take my kids to the KH, to read them Bible stores, and to place children's books with us. I simply refused each one. I told them that I had differences with the WTS. So, they what any JW would do, they did not respect my wishes and quickly went to my spouse. My spouse told them, "I don't think Skeeter would like that." So, then the JWs called the elders, who told them to back off because we were the parents. In your case, you can throw the issue off to your Head of Household Hubby!
You see, under US law, you have the right to parent your children and to bring them up in the religion of your choosing. Grandparents do not have this right.
What I also did was to "innoculate" my children against the JWs. I told them, "If anyone comes to you to talk to you about religion, church, God, or Jehovah . . . you stop them and tell them that you have to get mommy & daddy to be with you during this conversation." I repeat that to them every week, and then alot when the JWs are a coming near. Then, I told my JW relatives my rule in a matter-of-fact way.
Then, I also "explained" other religions to my children. I point out strengths and weaknesses of each. Library books, attend other churches, etc.
When my oldest was 8, my sibling came to town but was also going to the local Memorial. My 8 year old asked her what it was about, if it was like Christmas. Well, the sibling "light up" and explained that she was remembering Jesus death because he told us to remember him. So, I chimed in that some churches remember him once a year, but others remember him at every Mass with the bread and wine. I reminded the 8 year old of the Catholic service we went to with a neighbor friend and how they ALL partook of the wine and bread. JWs do it once a year, and only very few remember him with drinkng the bread and taking the wine. Well, JW sibling then gets high and says, "Oh, that's wrong to do it every time." To which I said, "In the Bible, when Jesus said to remember him, he did not give a set schedule and nor did he exclude people. Some churches do it once a year, and others do it more often. Go read the passage." Sibling shut her trap at that point. To which I then added on, "Jehovah's Witnesses big celebration is like a funeral for Jesus. It is not a celebration as you are thinking, honey."
Don't let your children go to the JW church without you. The JWs will quickly brainwash your children and, eventually, turn them against you becuase you turned your back against Jehovah. There are too many here on this board who have gone through this scenario. Do you want your children to write you.
"Dear Mommy & Daddy,
You are going to die in Armegheddon becuase you do not believe in Jehovah. You need to come back to the meetings. I will miss you when I am in Paradise...."
Those letters really do get sent (usually between divorced, mixed religion families).
Eight years old is just two years away from 10. And, 10, is the new age to be baptised. Do you want your child studying for JW baptism?
JWs have a warped sense of childhood. They don't really accept childhood. They try to make children into mini-adults. In dress, talk, behavior, everything, JW children are expected to be mini-adults. An extension of this is that JW grandparents think that the mini-adult has a right to accept an invitation to the KH, with or without the parent's permission. There have been stories on this board of JW neighbors cunningly taking non-JW neighbor kids to the KH. JWs don't respect boundaries, and if you and your husband are going to be parents . . . you need to set boundaries with your parents.
Encourage the grandparents to interact with you, your husband, and their grandchildren. At all times, put the ball in their court and keep an open door policy. Just take religion off the table. If your parents shun, your kids will get "shunning". Even children will find it against human nature if it should happen. Biggest turn-off JWs can do. Best thing you can do to innoculate your child against cults.