Mixing Ultramarine-geneseed with non-Astartes, and psykers to boot? Hm would make an interesting movie in how things can go horribly, horribly wrong (mutations and insane
Space Marines). I mean I could with skepticism maybe accept Grey Knights geneseed mixed with Ultramarine geneseed. But that would be stretching fluff a whole lot in my opinion as mixed-geneseed chapters has a history of things going very wrong for them.