HEADISPINNING- Are you sure your husband wasn't married to my JW ex-wife ? Sounds like a carbon copy of exactly what I went through when my JW children were 15, 13 , and 11 over 10 years ago. I was in a DFed state from 1998 ( the time of the divorce ) to 2002 and my JW ex-wife did EVERYTHING under the sun to interfere with my three and a half day per week visitation with my children. The children wanted to see me, however my ex-wife gradually tried influencing them against me. She'd make sure they were busy with friends in field service or had made other plans for them when it was clearly my time to have them stay at my home.
By 2000 the ex-wife's interference with visitations got SO bad that I requested a court appointed mediator who was neutral to both parties to help secure a fair visitation agreement that legally my ex-wife would HAVE to stick to or be in violation of the laws in our area. So things got better when my ex-wife saw I was playing hardball and that I wasn't going to allow her to break the laws of the land just to turn the kids against me. The kids started visiting regularly thanks to the work of the mediator and I had them three and a half days a week.
HEADISPINNING- Another thing you might want to consider is that the elders in your hubby's ex-wife's congregation may be influencing her to keep the kids from visiting you and your husband. What happened in my situation is that an elder in my ex-wife's congregation came up to my then 13 yr.old son and told him, " Your dad is DFed and you shouldn't be associating with him or seeing him ! " My son wasn't going to have any of it. He told the elder, " He's my dad, I love him and I deserve to see him ! " So don't underestimate the JW cults elders and the ressure and manipulation they not only put on your hubby's ex-wife, but also his children.
Legally as long as his kids are minors under 18 - WT society doesn't have a legal leg to stand on. It's against the law to restrict visitation with a divorced parent DFed or not , unless the child is endangered physically by doing so. So I'd tell hubby to stick to his guns, but remain calm and dignified through the process. Don't badmouth the ex-wife to the children as it will make YOU guys look bad to the children. They'll resent you for it. Just take care of your legal rights as provided by the law and keep unconditionally loving the kids. Try avoiding direct confrontations with the ex-wife. Use the legal mediation process . You may have better results. Good luck to you, Peace out, Mr. Flipper