Not a lawyer, dear Hubert (peace to you!), but most probably:
1. The statute of limitations has run. I don't think it's the same for malpractice as it is for, say, murder or child molestation (which never runs);
2. The courts most probably won't take the case (assuming a class action) due to:
a. The division among those who would say they were made to/restricted from... and those who will say they made their own choice...
b. Religion is a choice as is following religious beliefs (for oneself and one's minor children, even where that choice is/was/may be detrimental to a minor child)
c. And most importantly, there are laws NOW that protect children (for example, when a parent refuses blood/treatment, the physician can get a court order); however, the U.S. Constitution does not allow going BACK and prosecuting/suing someone for somethat that WASN'T illegal at the time it occurred. So, the only people who COULD possibly sue are those children who suffered damages SINCE the laws protecting them came into effect. The problem HERE, though... is that they'd have to sue their parents, who made the decision, as well.
Now, if anyone who was a "victim" of what occurred during the time you've mentioned died... and their legal counsel can prove MURDER on the part of the WTBTS (which, could possibly be done under the theory of reckless endangerment... but they would have had to KNOW they were endangering others, which they will claim they didn't)... well, that's a whole nuther thing.
I hope that helps and, again, peace to you!
A slave of Christ,
SA