When confronted with opposition from a group, such as at the negotiation table, the board of directors, or classroom, seek out individuals in private in breaks or when the group is not meeting together and communicate your perspectives without group peer pressure and psychological overhead. Sowing division.
This negotiation ploy is at least 3000 years old. In Szun Tsu's Art of war, his 23rd precept: "If he is taking his ease, give him no rest. If his forces are united, separate them." For example, an activist board member or shareholder can cause issues, ultimately, they want to be heard. Approach not only the activist but also other members whose votes you will need and listen to them and empathize, before communicating your perspective.
This is powerful for the divider. The first solution approach is to lobby. One on one negotiations with your best persuasive techniques will the individuals. Secondarily, pointing to a common problem, the enemy has untitled nations (e.g., during Otto Von Bismark's unification of the dozens of German kingdoms in the 19th century - Bismark pointed to France as Germany's natural enemy triggering the Franco-Prussian War) and companies (Ford, General Motors and Chrysler confronted with Japanese imports in the 1970s - 1980s began to co-train, martial resources and pass legislation around Just In Time production methods - after failing at old-time protectionism) and activists (civil rights movement bringing various complacent groups - businesses, unions, governments, college students, individuals - to see the hypocrisy and injustice).