Saving the game + Items in Inventory

[HappyMatt12345]

Obviously in Amnesia, you have the "Save" and "Save & Exit" options in the pause menu. However, in the Justine DLC, those options are not present (except from just "Exit"). Since I don't think Justine counts as a Full Conversion, just simply a Custom Story. Is there a way to implement this into a standard custom story? The reason why I'm asking this is because I had the idea that I just want to test. It involves using a save point to save the progress, similar to Resident Evil or Silent Hill.

Also, to save the game by using the save point. I wanted to use a certain item (puzzle item, to use on another entity) in order to save the game, also similar to Resident Evil. However, because I'm currently using the item as a puzzle item in Model Editor, the item in the inventory isn't stacked (meaning it doesn't have x2, x3, etc..., instead it uses more than one slot). Is there a way to make the item stackable whilst using it as a puzzle item (with the icon to replace the standard hand or white dot)?

Thanks!

EDIT: If my memory is correct, I think the save feature idea that I wanted to use was done before in a Full Conversion mod called Tenebris Lake. However, since it's a FC and not a CS, I'm not sure how it was done.

Sadly, I am pretty sure that this can only be done by edits made to the game config, which means you cant do it with a simple custom story. There is a guide on the wiki explaining how to create a full conversion mod, there are also a couple YouTube videos explaining this as well, but you need to make a FC to change any of the main game config files for a mod.