I'm going to have a Hatfield built with custom inlays. I'm a trout fisher so I want it with flies and trout. I know Custom Inlays and their wok with Hatfield, then I came across another maker who was super impressive. Does Hatfield happily work with other inlay makers?
Trust Arthur. His relationship with Custom Inlay goes back decades - he works with them for a reason. When I had my custom Hatfield, built, I had a unique design in mind; Arthur assured me that Bryan Englund et. al. at Custom Inlay could do it. Matter of fact, he strongly suggested that I contract directly with them for the peghead overlay, the fingerboard, and the heel cap "so that I don't mess it up." In fact, Arthur doesn't charge much of a markup for stuff like this, but I paid Custom Inlay directly.
Furthermore, Custom Inlay will NOT mess it up - and if they do, they'll make good (they were off a little on the heel cap, and they replaced it gratis).
Talk to CI and send them your ideas. They will send you scans proposed designs for them; you can suggest changes and work back and forth until it's everything you've hoped. Then they'll cut and rout. Not 'til then.
You will never go wrong taking Arthur's recommendations as they stand.