You could always do something custom. If they bump into each other, make them stop, shake their heads, take a step back, and find a new path You could even pick a random number to see what they do. Like if randomNumber = 1 they shake heads, step back, find a new path, if 2 they stand there looking like they're complaining to each other, 3 = they shake their fists at each other...
Just some random examples, not sure what you're making though.