PanMacmillan will have different option clauses for different books, depending on what's negotiated when they license the rights. Since you already have one set of YA fantasy novels with one publisher, and you would be submitting an adult crime novel, it wouldn't necessarily be the case that Macmillan, if they licensed the crime novel, would want any of your fantasy, and you could legitimately make the case that you can't option all your next novels since you already have an option clause for specific fantasy novels with another publisher.
However, this sort of thing is a lot easier usually if you have a literary agent, who has the leverage to do negotiations of having a whole client list, current and potentially future, and who may have contract precedents with Macmillan from previous deals where option clauses are concerned. So it might be time, since you're published and now generating a wide range of projects, to go looking for an agent. This would also give you better opportunities to sell foreign rights to your works. But even without an agent, (and I don't know that Macmillan accepts unagented submissions anymore; it's possible that they do or do in certain imprints

you probably would be able to negotiate an option clause that works for you, since you have previous contracts in place.
Does this help?
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