A class of cooperative differential games on networks is considered. It is supposed that players have the possibility to cut connections with neighbours in each time instant of the game. This gives the possibility to compute the values of characteristic function for each coalition as a joint payoff of players from this coalition without payments induced by actions of players outside the coalition. Thus the characteristic function is evaluated along the cooperative trajectory. It measures the worth of coalitions under the process of cooperation instead of under minimax confrontation or the Nash non-cooperative stance. The approach essentially simplifies the construction of the characteristic function and cooperative solutions such as the Shapley value and others. Also, it is proved that the proposed characteristic function is convex and as a result, the Shapley value belongs to the core.