So I was fighting with this problem for a few months now and I will ask again. Does someone know how to avoid the terraforming bug when swapping esp file to an esm file. And by terraform bug I mean when you swap the two files the ground changes that you have made in the esp are erased in the esm. This is a huge problem for me and my mod. It almost makes the completion of it impossible. So please I need help.
Thank you in advance !

Could you post a step-by-step walkthrough explaining how to reproduce the issue?

Sure.

1. Open the Creation Kit.
2. Open a Tamriel cell and make some ground changes. For example make a hill.
3. Save your esp.
4. Open TESvsnip
5. Open your esp.
6. Change it to ESM. Here is how to do it : Click the "+" in front of your esp name / Right click on TES4 / Then click "Edit" / Click the dropdown menu / Check Esm / Apply.
7. Save your esm.
8. If you test it in game you will see that the hill is gone and all terraform changes are gone too

9. HELP !

its not a bug. an esm cannot override another esm without using the proper tools (we do not have those tools)

it is technically possible to do it using CK's version control, but in order to edit a skyrim.esm record you would need to "edit" skyrim.esm's header file in a hex editor (which is probably an incredibly bad idea, since there are no hex editors out there that will do this without risking corrupting your file)

http://www.creationkit.com/Version_control



in any case, there is very little reason why anyone would need to use an esm for a mod. you really only need an esm for managing and communicating between multiple esp files (and allowing for one esp to work without the other for cases like modular install options), or if your mod is large enough that it is being worked on by several parties simultaneously

So I know that when the mod become too big for the esp you have to switch to an esm file in order the game not to crash. But I am not sure when the esp becomes too small for the mod. Is there a way to check that ? Thank you.

you dont have to do that anymore.

http://www.gamesas.com/topic/1388045-the-game-crashes-when-i-load-a-door-in-my-dungeon/

Are you sure that this will prevent the issue that I marked ? When a esp is too small for a mod.

And also is that true ? Can esp become too small for the mod ?