Is this a question?
If so, here is the answer: you have to add an @IncludeSomething=#@#MyVariables.inc option to the code. When you refresh / load the skin, when Rainmeter finds a such @Include option, it reads the appropriate file and adds its entire content, right after the section where the @Include option is placed.
You can add as many @Include options as you wish. The only thing you have to take care is to use different names for each of them. If you duplicate any of them, the second occurrence is ignored. So, for instance you can have @Include, @Include2 and @IncludeVariables options, but if you have all these three, a second @IncludeVariables can't be used (in fact, it can be used, but it's completely useless, being ignored).
Details: https://docs.rainmeter.net/manual/skins/include-option/