I'm not sure if this makes sense but because a Section 1 essay isn't really structured the same way like an S2 or an Adv essay (i.e. topic sentence, context, evidence analysis link), I've been taught to treat it more like a discursive essay but with a high academic register. So the way I incorporate my imaginative sections is after finishing my analysis of the stimulus they give us, line break "Consider a world, where xyz happens." then make an indent on the page (kind of like when they quote someone in news articles and have the line on the side) and write out the shortened imaginative section. And then after that yeah line break "In this world, xyz happens, this shows that literary worlds do this." Then return to regular critical structure.