The fact that a discursive piece explores a topic from various perspectives means that the wider range of ideas is an aspect of this type of writing that you can capitalise on in the event that you need to transform a discursive piece into an imaginative piece. In terms of how varied perspectives can be reflected in an imaginative piece, you could explore an event(s) that occurred in the life of a character(s), after which they learn that their perspective regarding a particular matter is not the only one and that there are other sides to the matter.
Unlike discursive writing, there is no emphasis on being unbiased when developing a creative piece. Based on this, another potential avenue is to explore an event(s) that occurred in the life of a character(s), after which they learn that their perspective with respect to a particular matter is flawed and are ultimately introduced to a more effective alternative.
In terms of your idea to incorporate your discursive piece as an element of a creative piece, I think that a way through which you could do this is to treat your discursive as the core element of an imaginative piece that is to be surrounded by other secondary events. For instance, a brief speech that is inspired by your discursive piece which you may place towards the end of your piece could constitute the culmination of your character's struggles throughout their journey.
I hope this helps!