Please protect these innocent children from this insidious cult, it's your job.
Look at all the heartache onl the ex jw boards and you will learn why. You need to protect the children's physical/sexual, spiritual and emotional well being. All of which could very well be compromised by being left alone with a jw.
If you want to keep these people in your life then never, ever leave them alone with the little ones. If you go into one room for something make sure someone else is there to monitor them. jw's have a thing called theocratic warfare, basically they are allowed and encouraged to lie to you (a non jw) because you are not really worthy of truth to begin with. They will try to indoctrinate the kids any time they can, bits and pieces here and there if need be.
You said, "My 5 year old is really smart and she would tell me if something was strange"- how would a 5 yr old know what is 'strange'? what is the world experience at 5? is shunning strange? is someone touching my bottom strange while they smile and tell me god likes it? is it strange to..... you get the idea. Adults don't even know when they are being indoctrinated how would a 5 yr old?
Do not believe them if they tell you they would not try to influence your minor children and they respect that blah, blah, blah. It is lies. I know from personal experience how far a jw will go to get a minor child in their grasp, in my case it was mentally & spiritually. We couldn't leave the jw alone with one particular child due to his incessant preaching at said child.