How do I create a list of things by combining independent variables in an action flow?

I have 8 individual page states that hold images uploaded by a user. You might think that's crazy but I found it is the most efficient way to hold images in a rotating PageView while allowing the user to rearrange the images.

But I have just found that I cannot find a way to group these 8 images together in a list and use it as a means to create a post (which should have multiple images). Basically the user will press a button to create a post, and one of the fields is a "list of images" but I can't find a way to pass this field all the images stored in the individual page states. Is this even possible?