jgnat posted on your other thread. I would always listen to what she has to say.... and pay no attention to my avatar. I'm a 6'3" 220 pound male.
I will give you the perspective of a guy who has fought the JW relatives for 22 years. I have two boys 22 and 19 and am married to a non active JW. My meddling MIL (a lifelong JW) went behind my back to try and indoctrinate my son into the religion when my oldest son was 10, and the end result was disastous for her....it did however cause a lot of unnessesary problems and nearly caused my son to be a social leper amongst his friends and schoolmates. Hopefully you can avoid that.
The JW's are a cult that believe that their organization is the sole channel to God. I wouldn't even begin to talk religion until you have spent a good month reading and asking questions. The best of .... links on the drop down menu at the top of this page are gold.
I wouldn't take the battle to them yet, I would let it come to you. And it will....big time.
JW's look down on any activities that take away from their organization and its activities. They are a cult, so they try to cut the individual off from any activity that doesn't benefit them. So they discourage higher education, extra ciricular activities including sports, spending to much time pursuing other interests such as music, art .....basically anything. None of their reasoning for discouraging these things are bible based nor can they be scripturally backed up. They are indefensable.
This is where I would pick my battle. Keep the kids active and social. As the kids get older, their social circle and activities become very important. I would make it a priority to immediately get the kids involved in sports (preferrably team sports), whether it is soccer, baseball. pee wee football or music or dance or karate....anything that is of interest to them. You could look into the local YMCA programs. They are still at an age where they don't have to be good at it to enjoy. It is a socialization process. Support them and let develop an appreciation for their activity and experience the comraderie that comes with an organized team activity.
The JW's will eventually start telling the kids that the extra ciricular activity that they enjoy is bad. JW's will never offer an alternative other than telling the kids that it is bad because it takes away from Jehovah. They are a one trick pony. If the kids have benefited from the social activities and made friends, then they will not let the JW thought process sway them.
If the kids don't have any activities that they enjoy or social life to lose then they may fall prey, however if their social life is established, then they won't give it up easily for anyone.
My son who is now 22 told me the other day how thankful he was that I insisted that he play Little League and especially HS football. He wasn't very good, but he developed a sense of teamwork and frienships that remain to this day.
Good luck!