How do i stop my dogs from fighting?

Unfortunately once bitches start to fight, it's often very hard to find a way back. Obviously you should have avoided any situation where there would be 'competition' ie offering one a bowl. Now this has happened, you should not leave them alone together, at least for now. It could just be a one-off thing, triggered by the food bowl, and with careful supervision, and avoiding anything that's likely to mean one wants what the other one has, they will settle down again. But again, it may now mean you have to rehome one of them, especially if there is injury involved. You say Poppy is the boss - obviously Shi-anne has other ideas. And the bottom line is they should be listening to YOU, above any pack order between them.