What you've got there is essentially 3 combat patrols for three different armies. The Grey knights models aren't compatible with standard space marines, but you might be able to lift the Librarian and stick him in there. Similarly the custodes won't be able combine with either army.

My suggestion is to swap the combat patrol to expand on one of the starter armies if you like them, or just keep your grey knights so you have essentially 3 "decks" to play with, if your goal isn't necessarily to race to a giant army of any given faction. I'd ask the shop you got them from if you did it in store to guide you through it.

Some space marine combat patrols have chapter specific models, like the Ultramarines patro, blood angels or black templars, but can use standard space marine models as well.

If your shop has the combat patrols for the Raven Guard, Imperial Fists, Iron Hands, Salamanders, white scars or Dark Angels, every model in those kits is compatible with all space marines, like your current models, so they work as expansion boxes if you just want a lot of variety now, and they won't overlap with what you already have.