By William Horsley BBC European affairs reporter

France and Germany plan a spectacular joint session of their national parliaments in Versailles on 22 January, the 40th anniversary of the "Elysee Treaty" on Franco-German co-operation.

Today's leaders want to show they are still in the driving seat of European integration, but not all is well in the French-German marriage.

Some French and German people can see the funny side of it.

Marianne marries German Michel (left) despite US objections

The Franco-German school in Versailles, near Paris, is a direct product of the Elysee Treaty - a bilingual showcase of joint French and German education.

Seventeen-year-old Katie and her class are taking part in a skit on the "Franco-German couple."

It opens with the "wedding day" in 1963: Marianne, the symbol of France, is marrying Michel, Germany's national cartoon character.

The American, identified by his cowboy hat, loudly objects.

Well done for the last 40 years - but for the future, be a bit more modest Arte TV anchorman, Vladimir Vasak

Germany, he protests, had promised it was "on our side".

But Marianne grabs her German partner by the ear, to show that from the start France means to be on top in this political marriage.

Nowadays, in reality, France and Germany are using their leadership in Europe to challenge American power in many areas.

Katie is glad she is at this school, which has made her fluent in French, German and English.

She wants to use her skills to go into an international job. But the treaty means little to her.

"It's just a piece of paper. We don't really know what's in it," she says.

Economic integration

In Strasbourg in eastern France is another creation of the treaty - the bilingual French and German TV station, Arte.

It's jointly funded by the two governments and the two nations' public broadcasting channels.

Vladimir Vasak: Open your arms to eastern newcomers

Arte will be showing the joint session of the two parliaments live. It is a political project to keep France and Germany as the "engine" of Europe.

But even here doubts are being heard. Arte's news anchorman Vladimir Vasak, wants the French and German governments to take more account of the former communist states of eastern Europe which are soon to join the EU.

His message to those leaders is: "Well done for the last 40 years. But for the future, be a bit more modest. Understand that you are not the only two leading countries in Europe. And open your arms to the newcomers in eastern Europe."

Vladimir himself is French, but the son of refugees from Czechoslovakia in communist times.

The Franco-German relationship is in search of ideas Andreas Schwab, Franco-German Forum

Strasbourg is a showcase of another pillar of the Franco-German alliance - economic integration.

The French city and the Alsace region have all but merged with Baden-Wuerttemberg on the German side of the Rhine river.

Search for ideas

Yet Marc Funk, working for the development office of the German border town of Kehl, says Germany's present economic malaise risks upsetting the partnership.

He blames poor political leadership.

"French firms have handled globalisation much more easily than German ones," he says. The main reason is the soaring costs of employing people in Germany.

Andreas Schwab: Reconciliation is no longer necessary

"Now more and more production has gone to eastern Europe, Asia or America. It's a problem for Germany."

In Paris, the Franco-German Forum is another champion of the "special relationship".

It publishes a magazine and website promoting co-operation.

But its co-president, Andreas Schwab, is worried.

In spite of the leaders' claims of new political triumphs for the partnership, he says: "The Franco-German relationship is in search of ideas. At the start the main point was Franco-German reconciliation, and the European Union."

"Now young people ask - what is the French-German relationship for? On the anniversary we do not want a party, or long speeches.

"What we need is a new project, and we do not have one."

William Horsley reported on the Franco-German relationship for Europe Direct, which can be seen on 16 January at 1730 GMT, on 18 January at 1630 GMT and 2330 GMT, and on 19 January at 0230 GMT and 1930 GMT.