I also had the same problem, so I decided to crate a python program that creates those within automatically. Here is the program:

import os
import sys

def process_directory(root_path, parent_within=None):
    package_name = os.path.basename(root_path)
    
    # Construir el nombre completo del paquete
    if parent_within:
        full_within = f"{parent_within}.{package_name}"
    else:
        full_within = package_name

    # Crear/reescribir package.mo
    package_mo_path = os.path.join(root_path, "package.mo")
    with open(package_mo_path, "w", encoding="utf-8") as f:
        if parent_within:
            f.write(f"within {parent_within};\n")
        else:
            f.write("within;\n")
        f.write(f"package {package_name}\n")
        f.write(f"end {package_name};\n")

    # Procesar todos los archivos .mo en esta carpeta (excepto package.mo)
    for filename in os.listdir(root_path):
        file_path = os.path.join(root_path, filename)
        if os.path.isfile(file_path) and filename.endswith(".mo") and filename != "package.mo":
            with open(file_path, "r", encoding="utf-8") as f:
                lines = f.readlines()

            # Quitar "within ..." si está en la primera línea
            if lines and lines[0].strip().startswith("within "):
                lines = lines[1:]

            # Añadir la línea correcta
            new_lines = [f"within {full_within};\n"] + lines

            with open(file_path, "w", encoding="utf-8") as f:
                f.writelines(new_lines)

    # Recorrer subcarpetas
    for subdir in os.listdir(root_path):
        subdir_path = os.path.join(root_path, subdir)
        if os.path.isdir(subdir_path):
            process_directory(subdir_path, full_within)


if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("❌ Uso: PackageCreater.py <ruta_carpeta>")
        sys.exit(1)

    root_folder = sys.argv[1]

    if not os.path.isdir(root_folder):
        print(f"❌ La ruta no existe o no es una carpeta: {root_folder}")
    else:
        process_directory(root_folder)
        print(f"✔ Estructura Modelica actualizada en: {root_folder}")