“Lewis A. Kaplan (born December 23, 1944[1]) is a senior United States district judge serving on the United States District Court for the Southern District of New York....Kaplan was a partner at Paul, Weiss.”
https://en.wikipedia.org/wiki/Lewis_A._Kaplan
“Roberta Ann Kaplan (born 1966), also known as Robbie Kaplan....was a partner at Paul, Weiss, Rifkind, Wharton & Garrison before starting her own firm in 2017.”
https://en.wikipedia.org/wiki/Roberta_Kaplan
I found no blood or family relationship.
Lewis left Paul, Weiss to become a judge before Roberta joined the firm.
Sure they are probably related somehow. They are both ethnically Jewish, both worked at the same prestigious law firm Paul Weiss, and both are going after Trump.