Kira von Meck in 1905 married Aleksander Zapolski who was a manager at one of von Meck's estates. He comes from polish nobility. They had 5 children:
1906 Konstanty - died at the age of 16 (accidentally shot himself on while hunting)
1908 Anna - she died in 1995, had one son Andrei (professor of High Energy Physics at the Indiana University). His son Nick lives in US and has 2 children Max (born in 2004) and Anna (born in 2007)
1910 Kira - she was killed by the officers of the Red Army in 1944
1912 Irena - died during II World War form typhus - she was a nurse during the war
1928 Jadwiga
Jadwiga is a professor of linguistics, she lives in Warsaw. She has 3 children (Wojciech, Stanislaw, Joanna), 13 grandchildren and 2 great grandchildren. Still active. In 1949 she married prince Czeslaw Puzyna (the family coming from Ruryk). Below please find some info about Jadwiga. After II World War Kira lived with her youngest daughter Jadwiga. She lived with her family till her death in 1969. She is berried in a Puzyna's family grave on Powązki cemetery in Warsaw.
https://pl.wikipedia.org/wiki/Jadwiga_PuzyninaFamily tree:
http://www.sejm-wielki.pl/b/sw.7664if you have other questions pleas feel free to ask me.