How to replicate an activity, making it a copy which gets the dates of the first when scheduling

Hi to everyone, I have searched and searched, but I couldn't find the answer.

I want to summarize a big project selecting only the activities I want, or groups of them.

"Level of Effort" activities are the best solution. BUT they only work when I select different activities as predecessors and successors. But what happens if I want to put in my summary just one activity? I am then not allowed to use a SS relationship and FF relationship with the same activity (not allowed to select it at all again).

Level of effort activities allow me to get this personalized summary of how is the project going when I schedule it, but if I want to replicate just one activity in my summary project, I can't. Is there a way to make an "slave" copy of the "master" activity?

This way, if the master gets modified (not by me), when I schedule my summary project, the "slave" gets updated with the new start and finish dates (the only data I want to preserve).

Thanks,