Along the same lines as Mari-Lou A's answer, I ran Google Books searches for "they concert" and "we concert," and found eleven unique matches published between 1996 and 2005.
From Political Science Quarterly (1996) [combined snippets]:
The states in question will ultimately have to decide whether to concert their actions or instead to act unilaterally and competitively to counter them. Whether they concert depends on both how severe the threats are and how each is affected by them. The more severe the threats and the more they affect all nearly equally, the more likely is concerted action.
From Benjamin Miller, "The International, Regional, and Domestic Sources of Regional Peace," in Stable Peace Among Nations (2000):
Leadership and mediation by a single broker should be more effective than that by several great powers, even if they concert their actions, because transaction and information costs are lower. All in all, a single dominant country will be better able and more willing to provide these goods than a number of comparatively equal powers, which are more likely to compete among themselves for regional influence than cooperate to ameliorate regional disputes.
From J. E. McGuire & Barbara Tuchańska, Science Unfettered: A Philosophical Study in Sociohistorical Ontology (2000):
Power is in its enactments, in its relations of alignment and counteralignment that configurate individuals and groups. Individuals as they concert together "are always elements of its articulation. In other words, individuals are the vehicles of power, not its points of application."
From James D. Wolfensohn, "Message from the president and chairman from the 2000 World Bank Annual Report" (October 2000), in Voice for the World's Poor: Selected Speeches and Writings of World Bank President James D. Wolfensohn, 1995–2005 (2005):
If we are to achieve the United Nations–based international development targets, we all need to work together. Halving poverty levels by 2015 is possible, but only if we concert our efforts in a new way.
From J.A. Wylie, The Papacy: A Demonstration (2002):
The mystery of iniquity worked as treason works. The conspirators meet in secret conclave, they concert their plans unknown to the world, they speak in whispers, but their schemes at length ripen, and now they come abroad into the light of day, and proclaim in the house-tops what they had hatched in darkness. So did the "mystery of iniquity" work.
From Wolfgang Storch, Mania Thebaia (2002) [combined snippets]:
Those myths are written into the biographies of each and every one of us. Familiar and forgotten. When they surface, they differ from our memory of them. Here they concert to disconcert. Four approaches to the meaning of tragedy today, four attempts to find an idiom commensurate with what it has to tell us.
From UNI Info (2003) [combined snippets]:
"It's only if we concert our actions that we can be successful in Europe and demonstrate to employers that we can find each other."
From Kenneth Liberman, Dialectical Practice in Tibetan Philosophical Culture (2004):
How does a debate become coordinated and how is a structure for analytic thinking developed, that is, how do Tibetan scholars clarify the philosophical issues they are addressing and how do they arrange their discussion in a manner that enables them to listen to each other carefully while they carry out their inquiries? We offer a close description of the philosophical practices of Tibetan scholar-monks and examine in detail how they concert themselves to produce a well-ordered philosophical debate.
From Council of Europe, "Apologie du terrorisme" and "incitement to terrorism" (2004):
Article 25[:] Forms of conspiracy [under Lithuanian law]
The forms of conspiracy are a group of accomplices, an organised group and a criminal organisation.
Two or more persons are called a group of accomplices if at any stage of a criminal act they concert to commit, to continue or to finish a criminal act and if at least two of them are principles.
Two or more persons are called an organised group when at any stage of a criminal act they concert to commit several, either serious or very serious, offences and each member of the group performs a certain task or has a different role.
From Turkish Policy Quarterly (2004) [combined snippets]:
In some important parts of the world, notably Russia, the EU countries have failed to agree on effective common policies—but they do have very similar interests. Silvio Berlusconi, Tony Blair, Jacques Chirac and Gerhard Schroder have each sought a special relationship with Vladimir Putin. They have cosied up and refrained from criticizing the Russian president, lest they lose their privileged position to another European leader. Sooner or later they will learn that they stand a better chance of fulfilling their objectives if they concert their efforts.
From Emile Franz, The Shepherd (2005):
You understand, my friends, that as soon as the priests realize there is nobody in charge, they will act on their own and there will be anarchy here and we will be, God forbid, their first victims. I am then suggesting that we concert and decide of two or three other shelters where we know for sure to find each other, if while we are in the streets, we are caught by some riots. The Master would tell us not to fight but to retreat.
Additional recent matches may be uncovered by running similar searches for "can concert," "may concert," "should concert," and "will concert." Not every match will use concert in the desired way, and some of the matches will be quotations or reprints from much older sources; but many will be suitable, and they are easy to find by clicking the 'Search in Google Books' link for a specified time period and phrase. Here is the link for the complete set of searches I ran: they concert, we concert, can concert, may concert, should concert, will concert.