Duplicate Sub page post on Main page

I found your plugin (Multisite Post Duplicator) very useful for copying the posts from main site to sub sites.
But is there any way i could enable copying from sub site only to main site?
So that users could copy their posts to my main site but not to any other sub sites between them?
Im thinking that editors or admins of sub sites could have an option or checkbox – Post on main site.

Do you understand what would i need from what i wrote?

I thank you very much for any answer and help.
And also a big thank you for making this plugin really.

The page I need help with: [log in to see the link]