In reply to Adalbert Thomalla.

If you have programming questions, you should submit them to the SAS Support Communities. I cannot provide personal assistance.

The documentation for the STORE statement states that "The iml action does not append to an existing storage table. If you open an existing table and write to it, all the previous contents are overwritten."

Usually, define all modules in one file and use STORE MODULE=_ALL_ to store them. I can then use LOAD MODULE=_ALL_ to load the modules.

If the module definitions must be spread across multiple files, you can try to use %INCLUDE statements to read all the definitions, then use a single STORE statement. Depending where you are running the program (in the cloud versus locally), the path to the files might be hard to specify, which is why I prefer the former solution.
See also the article "How to use Git to share SAS programs."