It's a very good idea to use a common naming convention when managing properties with MPM.
Name all managed "child" properties with a common prefix [prefix] - [child property name] eg. G - Main site
Name all launch properties with the MPM extension with a prefix to match the managed "children" of that "Parent" property [prefix] - [parent property name] eg. G - Parent Template
Name all rules, and Data Elements within the parent property [prefix] - [element name] eg. G - Page Name
It's important to be mindful of the libraries you leverage with MPM. The full list of available libraries can become hard to manage within the extension. You also do no need to publish the parent library for it to be available to MPM so managing your available libraries in development can be helpful to keep the list manageable.
Many clients only have one library in their parent property.
When making updates in the parent library it's wise to keep the working library set to the library you plan to syndicate to the child properties.