33 The institutes engaged in missionary activity in the same territory should find ways and means of coordinating their work. Therefore, it will be very useful to have conferences of Religious men and unions of Religious women, in which institutes of the same country or region should take part. These conferences should ask what things can be done by combined efforts, and they should be in close touch with the episcopal conferences. All these things, with equal reason, should be extended to include the cooperation of missionary institutes in the home lands, so that questions and joint projects can be settled with less expense, as for instance the formation of future missionaries, as well as courses for missionaries, relations with public authorities and with international or supranational organizations.
Source: Ad Gentes (Vatican.va)