How can I grant access to my blog to only one person?


I have just installed Elgg 5.0 to test and use it in an educational context. It is straightforward and intuitive to use, but I noticed that I can only share my blog with friends, the public, registered users, or a group of friends. However, I would like the author to be able to share the blog only with specific individuals or just with their teacher. Is this possible? The only solution I found is to create a group of friends with only the teacher inside and grant access to the blog. While this is a solution, it's not very practical. Is there a more intuitive solution or plugin available?

M1K :)