Out of many beneficiary activities performed by Diogenis D. Vlavanidis, the emphasize should be put on his role of the founder and Chairman of the Serbian Committee for the Reunification of the Parthenon Sculptures. The Committee was founded in Belgrade on May 24, 2002 with the goal of organizing activities that would contribute to return to Athens the Parthenon Sculptures exhibited for over two centuries in the British Museum in London. With the  foundation of the Committee composed of the most prominent Serbian intellectuals, Diogenis D.Valavanidis continued work started by esteemed Melina Mercouri, convinced that her persistent attempts to return to Athens looted Hellenic cultural heritage dispersed all over the world, represent strong cohesion power that brings together Greeks around the world.

The same fate befell the Serbian churches and monasteries in Kosovo and Metohija. Their existence at the very place of their origin, represents the core of the Serbian national being, its national flag and anthem. The "Center for the Protection of the Serbian national identity" was founded for this very reason, and it operates under the "Committee for the Reunufication of the Parthenon sculptures-Melina Mercouri". As a long time friend of Melina’s, and also of her husband’s, Jules Dussen, after her death (March 6, 1994 in Memorial Hospital in New York), Diogenis D. Valavanidis received a consent from Mr. Dussen, that only the Serbian Committee (there are 17 in the world), has a right to bear the name of his wife - Melina Mercouri. With this gesture, Jules Dussen, a well known American director, apart from proving his friendship, not only extended a great honor to the Board but also to Serbia as a whole. He also accepted to be a life long honorary President of the Serbian Committee.

In several public appearances Diogenis D. Valavanidis categorically declared: "When loving its country, one must always bear in mind that its people will exist for as long as its tradition, religion and language are nurtured. This idea has always held the Serbian people together, which is confirmed by the fact that they had survived, especially during the 500 years under the Ottoman Empire. This is due to the fact that Serbs held fast to their traditions, religion and language. They celebrated their patron saints, and had their children baptized. Actually, that's the testament that that we must never forget. "