The Hellenic Red Cross can help you, if you are in Greece and you have lost contact with family members due to armed conflict, migration or natural or man-made disasters. It doesn't matter if your family member was lost in Greece or in another country, they will assist you in looking for your family member. To help, you should bring recent photos of the missing family member and also the details of any ID documents that you have for them. The Red Cross will also want to know where and when they were last seen.
In Athens and Thessaloniki you can go to the Multifunctional Centers of the Red Cross. They will have interpreters and will be able to make an appointment for you with the employees who will assist you with finding your family member. In Athens it is best to go to the Multifunctional Center from Monday to Friday between 8:00 and 15:30, as there will be interpreters available at that time. Here is a pin for its location: (Kapodistriou 2, Athens 106 77).
The Multifunctional Center in Thessaloniki will be able to serve you between 10:00 and 14:00 from Monday to Friday. You can find its location under the following link: (Ionos Dragoumi and Vamvaka 1, Thessaloniki 546 31). If you don't have the possibility to go to one of the Multifunctional Centers, you can call the hotline of the Red Cross: +30 210 514 0440. They will be able to tell you if the Red Cross also offers the service to restore family links close to your location.