1) my sister was married for more than 10 years, then divorced
2) she was more that 62 years of age on January 1, 2016 when the new rules went into effect
3) her ex is past full retirement age and collecting benefits
4) she has now reached her own full retirement age (66)
5) is she "grandfathered in" under the Bipartisan Budget Bill of 2015 and permitted to file for a RESTRICTED application for benefits based on his record without being DEEMED to have filed for benefits based on her own record, so that she can continue to accumulate DELAYED RETIREMENT CREDITS on her own work record while collecting on his?
Yes, but your sister must be currently unmarried in order to qualify for divorced spousal benefits.