Is it your brother or your dad with a non-believing wife? I understand it is your sister-in-law? I hope she is Internet savy to be informed about the facts about JW history and manipulations. Of course, you have to be careful what you say to her about JW stuff, because she won't understand the confidentially you would need.
The WT has 'always' had a stance of not talking to relatives who were previously active JWs, that were DF'd. But now-a-days, there is getting to be a higher percentage of those leaving with voice/personal opinion, and the WTS does not have the percentage influx of new members by comparison. So the situation is very threatening to the GB and therefore the meetings, at the Kingdom Hall, assemblies, and circuit overseers are stressing shunning family members more frequently. The GB hate it that family members have more love for their family versus the GB.