In a way my chapter has mixed geneseed in that the marines originate from many different places, so nearly every geneseed type is present in the chapter- though (as far as I am aware) there are no marines who combine geneseed in themselves.
After reading the High Lords of Terra bit, Im glad I mention them decreeing the formation of my chapter- which admittedly they then put under Inquisitorial control.
I have to admit that the Knight's background is rather peculiar, possibly even implausible, but hopefully I've written it in such a fashion as to seem that it was simply a rare event rather than an impossibility.
Glad I haven't written them into any major, well known, campaigns though
