Based on above, I will handle initiative as such:
When it comes time to roll initiative, I will look at all of your characters, mark their initiative bonus, and roll for monsters and PCs all at once. I will then say what the initiative is. if there is a point where multiple PCs go in a row, the PCs go in the order of who posts first or in the order they say they want to go in (for example, if PC1 and PC2 can go in any order, but PC1 says they want to go after PC2, that's what would happen. Otherwise, they would go in order that they post).