Arbitration of 232 signals

My system consists of (2) PICs, and a third 'device' receiving/transmitting 232 signals. Both PICs need to talk to the 'device' via 232.' The device only has one 232 port.

So how can i separate communication between the two PICs? Do I have to use a third micro to separate the signals?

Any have or know of a buffering algorithm i can use as a template?