How we change what others think, feel, believe and do
Divide and Conquer
Cause confusion in the enemy camp. Get them at each other's throats so they pay less attention to fighting you. A way to do this is by paying more attention to one person or one group in a broad field of others, or by sowing false information.
Initially put more effort into persuading the more sympathetic person. Then when you have convinced them of your argument, work together with them to persuade others. You may also have to put in effort to keep them apart, particularly if those who are strongly opposing you are also working on the sympathizers.
When they are arguing amongst themselves, propose solutions that the key people will accept and which will support their internal negotiations.
A side member of a negotiating team spends time with some of the younger members of the other side whilst the main negotiations are going on elsewhere. In their discussions, they touch on how the ideas from these bright young people are being ignored by their superiors.
A negotiator and a colleague 'privately' talk about how one person on the other side is more successful than another. They know that they are being overheard and their talk is designed for the listener.
A negotiator hints in an aside to the other person how one solution will allow them to win some of their internal battles.
It is common that negotiating team members have different views and that some are more hard-line while others are more moderate. The members will have different motivations, including their desires to be on good terms with you and to conclude the negotiation sooner or later. If you can understand these (watch body language, listen to words, etc) then you can test your assessment in breaks and other times where you may talk privately with them.
If you can get the other side to take their eye off the substantive ball then you can consequently gain control of the proceedings. When others disagree with one another, then one may well take your side in order to win points against their internal opponents.
When there are two other people, such as a married couple, then views may be quite different. Watch for the dominant partner then direct innocent questions at the quieter one to test their views and also to see how the dominant partner reacts.
In team negotiations, people with non-direct roles such as note-takers may be approached to test their roles and their ability to influence others.
This, of course, is a hazardous strategy which can backfire if they discover what you are doing. To succeed, it must be executed with great care and finesse.