[SectionsToSave] how to insert it inside Config with C++?

My goal is simple here, I need to read/save few of my values in one of these:

I am developing the plugin, in order it to work, user’s Project must have [SectionsToSave] specified in one of the Project\Config\DefaultSomeConfig.ini file, so my plugin would be able to save my values inside .inis at Project\Saved\Config\WindowsEditor\SomeConfig.ini(screenshot above)

By far, the only way I know - is primitively insert it by hand, manually in that .ini file, like so:

[SectionsToSave]
+Section=MySection1
+Section=SomeAnotherSection

It works. But how do I do it automatically? There is should already exist some proper functions to it, and it is just me - fail to find it.

And I definitely won’t read/write to that file directly to place that stuff, that is to much work and risk to mess things there. People might already have such [SectionsToSave] with multiple existing +Keys in there specified.

What is correct way to do it?