Downvoted.

For games where there are multiple agents interacting, the optimal strategy will usually involve some degree of weighted randomness. If there are noncommunicating rational agents A, B, C each with (an unsplittable) $1, and charities 1 and 2 - both of which fulfil a vital function but 1 requires $2 to function and 2 requires $1 to function, I would expect the agents to donate to 1 with p = 2/3.

A rational agent is aware that other rational agents exist, and will take account of their actions.