I think you might consider some attempt to locate those kids of your brother.
You never know how much good some family contact can do them.
I hear from them, but very infrequently. They have left the Jw's in the wrong way. They have leaped into bad relationships and substances that will only harm them in time. [Ironically, it was similar choices that set up the time-bomb disease that killed their dad].
The older one will never go back - she in fact never joined the religion. The middle daughter is hooked up with bad com-padres from what I have seen and is very unstable. I have tried talking to her, but she is in her own world and keeps moving around, so I don't know from month to month where she it located, or her situation. The only boy, now about 20 or 21 I think, the youngest, tried to stick it out with the Jw's after his dad died, but gave into sexual pressure and got disfellowshipped. He stayed in the area where my brother lived, so I worry that he might bottom out and go back to the Jw's eventually. They were his family, since that was all he ever knew - his flesh and blood family [my sister and I and his granddad], were way out of the picture while he grew up due to geography, and his built in prejudice against those not in the 'truth'. I was until he was 15 or 16, but we did not live close.
None of the three of them has made good choices it appears so far. That is why I said that I think they would have been better off staying in the religion until they were older. Hopefully they will get a grip and start acting responsibly in time.
Jeff