I have 2 O's with a Jag, they are all about the 8 inch mark, the Jag has set up his territory at one end of the tank and the O's roam the rest but when they go into his part of the tank it's all gill flaring with the occasional lip lock. The Jag will have his own tank soon though.
I'd say providing there is enough space for the Jag to set out a territory leaving enough space for the O to swim you should be ok for a while depending on their sizes.