This happened a few times, back in the 70's, in the congregation that I went to. There were a few families who were jw's, divorced and remarried, had (physical anyway) custody of their children, but the divorced spouse was non-believing and wanted their rights to the children.
One family, when the father of the children went to court to get custody of the kids, picked up and fled the country. We later learned they were in Costa Rica. I remember at the time, even though I might have been 14ish, thinking this was really weird. Ends up, they moved back to this country years later, and the children ended up looking up their father and leaving the truth (and the mother who kidnapped them) anyway.
Another story, one family who started coming to our congregation in the late 70's. the father kidnapped the children away from their non-beliving mother, in the country where they were born, Nicaragua, and brought them here to the states. THe kids had no clue where their mother was for a good decade or so. The mother hired a detective, found the kids, who were adults by now. Neither child remained a witness and one went to go live with the mother.
SO, was this some weird trend back when i was growning up, (things seemed to be way more fanatical back then) or does this type of stuff still happen?