I am a US Citizen and I petitioned for my divorced sister to come and join me from the UK - she is in her 60's.
This was about 5 years ago. She got re-married a couple of years ago and now her I-797 has been approved for her permanent residence here in the US. What should she do now or when the interview comes up to ensure she can come to the US and bring her new husband with her. He has not filed any paperwork yet??

She and her husband apply for the immigrant visa together at the US consulate or embassy.

More importantly, its not the I-130 approval (the I-797) that is important as the priority date and the current processing date for that preference classification (FB-4).

The PD is on the I-797 receipt notice and tdhe I-797 approval notice, top left hand corner. That date must be current with the most recent DOS visa bulletin for FB-4. it usually is about a 10-12 year wait. When it is current, then your sister and her husband apply for the IV. According to the June VB http://travel.state.gov/visa/frvi/bulletin/bulletin_4497.html it is about an 11 year wait, as they are on August 15, 1998. Good luck.