It would be helpful to know what kind of "Arbeitsgemeinschaft" is being referred to. In any case it is clear that the remainder or the rest of the partners participating in the group are being designated as such.
If this is business (e.g. financing) you probably mean a consortium and not a working group.

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Note added at 2004-02-09 07:36:59 (GMT) Post-grading
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In my experience a joint venture is usually established between a transnational firm and a local company for the purpose of doing business in the local company\'s country (e.g. VW in China). A consortium, on the other hand, is a national or transnational business unit which a number of companies hold shares, founded for the purpose of combining finances, expertise or sharing risk in the cases of carrying out large projects e.g. Eurotunnel (tunnel under the English Channel/La Manche).