First bbp85 we all join you in prayer for the salvation of your family. And, no one on earth knows who will respond to the gospel. So, there is always hope they will come to the truth.
Fact is, they are following a false gospel ( gal 1 ), they have another Jesus ( 2 cor 11 ), and follow one of those false christs.
Your job is to share the gospel with them and to pray for them, so do it.
Listen to the catholic podcasts on witnessing to Jehovah’s Witnesses. catholicxjw.com/doctrines.html Read any book you can find on witnessing to them, even protestant ones.
Be Prepared to give an answer ( I peter 3:15 ). preach to them in and out of season. Don’t use Romans 2:15 as an excuse to avoid doing your part. Seek out others who are ex-jws, to bounce ideas off of for sharing with your family.
Use the overlooked apologetic of sharing praise music with them.
Galatians 1:6-8 (New International Version)
6I am astonished that you are so quickly deserting the one who called you by the grace of Christ and are turning to a different gospel— 7which is really no gospel at all. Evidently some people are throwing you into confusion and are trying to pervert the gospel of Christ. 8But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let him be eternally condemned!
2 Corinthians 11:3-4 (New International Version - UK)
3 But I am afraid that just as Eve was deceived by the serpent’s cunning, your minds may somehow be led astray from your sincere and pure devotion to Christ.
4 For if someone comes to you and preaches a Jesus other than the Jesus we preached, or if you receive a different spirit from the one you received, or a different gospel from the one you accepted, you put up with it easily enough.
For false Christs and false prophets will appear and perform great signs and miracles to deceive even the elect—if that were possible.
2 Timothy 4:2
Preach the Word; be prepared in season and out of season; correct, rebuke and encourage—with great patience and careful instruction.