Writing posts within a post

Hello,

I am quite new to wordpress in general so excuse me if I am being a little blunt in my question.

So, I basically want to have certain posts related to a particular post.

For eg: A post where one lets say talks about a movie “XYZ”, there are 2 posts say “Music for Movie XYZ” and “CGI effects in Movie XYZ”.
I basically want the 2 child post links for each parent movie post in the sidebar.

I have tried the alpha version of WP Sub post plugin but it is not good for the sidebar problem.

I have tried using sub-categories and making a separate category for each post and then sub-categories for each child post. Here, the problem is displaying the links on the sidebar as the available plugins will display all sub-categories and not for the particular category of the post.

The website I am working on has 2000+ posts and so anyway having 2000*X categories is not feasible.