The O.P.A.I.E. (Organization for the Care and Rehabilitation of Israelis of Greece), born of the post-war period, is the fruit of 5 years of efforts (1944-1949) by the leaders of the K.I.S., prominent Greek Jewish legal co-religionists of of that time as well as Jewish-Palestinian and international Jewish Organizations.
OPAIE inherited the property managed by YDIP (Israeli Property Management Service) and later KYDIP (Central Israel Property Management Service), i.e. real estate in all regions of Greece as well as minimal movables (valuables). The bulk of the real estate was of course in Thessaloniki.
Brief history of the establishment
 O.P.A.I.E. was founded on the basis of B.D. which was published in the Official Gazette 79/t.A΄/29.3.1949. This Royal Decree was issued in execution of A.N. 846/1946 (Government Gazette 17/t.A'/ 22.1.1946.
The publication of B.D. of the 29th March 1949 is the culmination of almost four years of efforts by the leaders of the KIS to issue a decree in execution of A.N. 846/1946 "regarding the abrogation of the State's right of inheritance over the remaining Israeli properties". The delay in issuing the B.D. due to the fact that it was connected to a pending case of a Greek politician's plot of land in Palestine. In order to settle this matter, the KIS acted and the purchase of the plot was made in cooperation with international Jewish Organizations.         
The NPDD with the name OPAIE included the schooling (undisposed, abandoned) properties of the Greek Israelites who died during the racial persecutions of 1943-1944, as long as they did not leave heirs or relatives up to the fourth degree.
OPAIE, according to B.D. of 29/3/1949, received, in principle, the properties managed by KYDIP (Central Service for the Management of Israeli Properties established by Law 1180/20.1.1944).
KYDIP was created by the Greek government as a continuation of the similar service YDIP (Israeli Property Management Service) which was created at the suggestion of the Germans in 1943 (Law 205/29.5.1943 "on the management of Israeli properties confiscated and abandoned by the Occupation Authorities »)
The object of the YDIP was the supervision of the management of the above-mentioned properties of the region of the General Administration of Macedonia. The competence of KYDIP was extended to the whole of Greece except for the General Administration of Macedonia. Later, KYDIP (Law 1977/10.10.1944) changed its name and was called the Central Service for Liquidation and Return of Israeli Assets.
The gesture of Greece for the establishment of OPAE, despite the long time of negotiations, was exemplary and was praised by the world public opinion and the organizations, Jewish and non-Jewish, abroad.
OPAIE took over properties managed by YDIP, with delivery and acceptance protocols. These properties were located
outside of Thessaloniki and in the cities of Didymoteicho, Kavala. Alexandroupolis, Florina, Chania, Ioannina, Serres, Orestiada, Kastoria, Komotini, Xanthi, Corfu, etc. But through his services or from testimonies, other properties were also identified. In most of these cities there were also local offices with a responsible partner or lawyer which were abolished in time.
During this time, he managed a total of over 5000 real estate cases. Many of them were leased, or had been granted by the Greek occupation authorities to refugees, the homeless, the needy and the afflicted. A major social problem arose with the agents of Jewish commercial enterprises in Thessaloniki, as well as with the tenancy law. Until 1979, there was an organized local office in Thessaloniki with technical staff who also identified many properties that had not been registered or handed over by the YDIP. The local council made decisions which it communicated to the Board of Directors. which met in Athens, where the headquarters of the Organization was. OPAE was usually co-located with KIS.
The first board consisted of Asher Moysis (chairman), Mino Levi (vice-chairman), Daniel Alkhanati (mandated advisor), Peppo Benuziliou, Moysis Karasso, Roberto Raphael, Daniel Alkhanati, Victor Vechoropoulos, Mino Matsa, Elio Negrin.
Since then they have managed 25 Boards of Directors. under the chairmanship of Viktoras Semach, David Amarilios, Anselmos Mourtzoukou, Markos Osmos, Lazaros Eliezer, Edgar Allalouf, Aaron Asher. The current president is David Tarabulous.
OPAIE's purpose and role was to rehabilitate co-religionists who survived racial persecution. The mechanism, based on the legislative provisions, functioned as follows: From the day of publication of the founding law and for six months (that is, within 1949) those who had relatives who perished during the Holocaust could claim their property with a single application - declaration to the Organization and of course provide proof of their kinship (up to 4th degree). 3600 on-time or overdue declarations were submitted. 
Subsequently, and for 20 years (until 1969) those who did not submit declarations and asserted inheritance rights had the right to file lawsuits against OPAIE claiming property. OPAIE's legal service examined each application and decided whether the applicant really had an inheritance right or not and issued a decision on inheritance right. In a positive case, the property was assigned to the declarant and if rents were collected, they were assigned as well. Returns were made by decisions of the Board of Directors and the Local Council of Thessaloniki.
It should be noted that in the event of claims, disputes and encroachments, lawsuits were filed either by OPAIE or by opponents against OPAIE and thus legal battles were a large part of the Organization's activity.
After the real estate was returned to beneficiaries and sold (for its maintenance), OPAIE, following decisions taken at nationwide conferences of the Jewish Communities, continued the work of restoration through KIS and Communities. This was done by donating properties either to Communities or to the KIS itself.
today's situation
Today OPAEE has few properties left which it manages. However, for the last four years, the Land Registry has begun an intense activity to locate properties of "unknown" owners or to review cases of properties that had been put on file due to lack of information.
The OPAIE archive consists of real estate files, case files, protocols of delivery and receipt of real estate from the YDIP, applications of real estate claimants, inheritance decisions, minutes of meetings and conferences, land register with streets in the name of the owner, portions of the mortgage office, registration sheets of movable property, statements destitute, business situations, etc. This file was located in Thessaloniki but, when the local office was closed, it was moved to Athens. A small piece of it is in the Jewish Museum of Greece which also took care of the preservation of these documents and copies are also in the Jewish Museum of Thessaloniki.
From this archive one can derive valuable information about the history of the establishment and operation of OPAE, but mainly about the areas where Jews lived, names and number of Jews who died during the Nazi occupation mainly due to transportation to the camps, type of operations and occupations, items recorded and apparently confiscated, names of property grabbers, indicative number of people who emigrated before the occupation to save themselves, and also afterwards.
Indicatively, we quote documents from the Organization's archive
The Compulsory Law, A.N. 846/1946, by which the State waives all its rights over the inheritances of the Greek Israelites killed in the Nazi camps who left no heirs and no will.
The Official Gazette (No. 79/t.A'/29.3.1949), where the founding legislation of OPAIE is published, which provides for the transfer to the Organization of the properties of the exterminated Greek Israelites in the camps.

Declaration of relatives claiming inheritance rights on the property of a deceased person
Greek Israelite camps.

of the deceased does not pass to him due to the existence of heirs.

Document of the National Welfare Service, General Administration of Macedonia, dated 2.4.43,
and with a stamp of the YDIP (Israeli Property Management Service), by which it is granted
in a refugee family related to a Jewish family in Thessaloniki.
(The first shipment by train of deportation of Jews departed from its railway station
Thessaloniki, bound for Auschwitz on March 15, 1943).

1948. Post-war housing approval in a Jewish property in Thessaloniki. Apparently the owners don't
they survived and OPAIE was not yet established to take over management.