Attach Images after More tag

Hello, I am currently making a website which is for the younger audience. What I’m looking be able to do is to have a multiple upload image box underneath the main post textbox, and when it is posted, these images appear only when you click on the “Read More” link after the main post content.

I know it’s achievable by using the “more tag” in the main post, and then insert the images after it, however this could be confusing for the target audience of who will be using the back end area.

Cheers!