Fixing the leak is the best solution. Much easier and more realistic with a team of one (yourself) than it is with more than one.

While we can all probably give examples from personal experience equivalent to the real estate agent leaking the minimum price, my personal favorite resulted in the current border of California. Ever wonder why the West Coast border between the U.S. and Mexico is between San Diego and Tijuana? At the end of the war that resulted in this border, there were American troops occupying Mexico City. Why draw the line there? Turns out that the U.S. negotiators had a list of must-gets and nice-to-haves. Alta California and Colorado country were must-gets. Baja was viewed as a desert waste and a nice-to-have. The list got leaked to the Mexican delegation by an American personally acquainted with one of the Mexican negotiators, so the Mexican team dug in their heels and wouldn't give up Baja. Point: keep negotiation teams small. Fewer leak-points. One (yourself) is best, because only then do negotiator interests exactly correspond with YOUR interests.