Hey screwface!
Sorry to hear about the struggle. Yup, spiritual blindness is a debilitating disease. And yes there is a medicine - one that the Watchtower surreptitiously attacks and is secretly terrified of. It is called the "good news" - just not the Watchtower version of it.
You might recall that when we door knocked we were told that we were "publishers of the good news" when in fact we were "publishers of religion". The two are polar opposites, especially in the area of self-righteousness or works-righteousness - versus - gifts-righteousness or IMPUTED righteousness. Paul has a lot to say about this especially in Romans 3 and 4. Jesus too had a lot to say in Matthew 23. If I was told I could have only 3 chapters in the Bible these would be the ones!
In short you might want to ask your nephew and parents to study the "good news according to Paul" with you. They most likely will be completely stumped. Persist by helping them to use the Watchtower library search tools to count how many times the Bible speaks of the "good news" (±152 times). Then get them to count how many of the Bible's references to the "good news" are by Paul (±85 times, ie more than half!!!). It is at this point that they will either begin to allow or deny the holy spirit chance to convict them of their ignorance and dysfunction.
Don't let them bring in an "expert"! Haven't they been "publishers of the good news" for decades? You want THEM to study the "good news according to PAUL" with YOU.
It is not possible for an honest hearted person to continue pursuing the full unabridged "good news" ABOUT JESUS (not about doctrine and dogma) and remain blind and captive to the Watchtower. It took our family 3½ years to get out intact!
The "good news" was expressly designed to properly break both spiritual blindness and captivity as one can see in this paraphrase of Isaiah 61:1:
"The spirit of the Sovereign Lord Jehovah is upon me [Jesus], for the reason that Jehovah has anointed me [Jesus] to tell [the] good news to the meek ones [sheep or wheat]. He has sent me [Jesus] to bind up the brokenhearted [spiritually deprived and unregenerated], to proclaim [spiritual] liberty to those taken [spiritually] captive [by religion/ists] and the wide opening [of the spiritual eyes] even to the [spiritual] prisoners [of religion/ists]".
Greetings
Fernando