I didn't find a record of Olga's evacuation in Yad Vashem site, only Lazar and Karina (the child).
When I searched there Yurovski from Lubny, Krivoy Rog and Zolotonosha, I found questionnaires submitted by Joseph Kaminsky (in 1997) and Isabella Kaminsky (in 2011). They both lived in Israel. The questionnaires have their address. You may try to find them or their descendants in Israel. I am sure that all people of this surname from Lubna and Krivoy Rog and Zolotonosha are all relatives.
You now do not known whether Lazar and his daughter Karina stayed in Magnitogorsk or returned after the war. If they have preserved some documents in the archive (in Magnitogorsk or Donetsk or elsewere) and these documents are younger than 75 years old, you can not accessed to them.
You can try to find out where Lazar worked in Magnitogorsk. This information may be in a card that stored in the Red Cross Search Center in Moscow. There may also his address in Magnitogorsk in 1942. But now the Red Cross and all our archives are closed for quarantine.