XF 2.1 How can I hide threads by user criteria?

[Improvs]

I'm trying to figure out how to hide special threads from users who didn't reached at least 10 messages.
Can you advice me, which function i need to looking for? And where?

 

[Mr Lucky]

I'm trying to figure out how to hide special threads from users who didn't reached at least 10 messages.
Can you advice me, which function i need to looking for? And where?

Those threads need to all be in a forum. You then use that specific forum permissions to hide from registered use group.

You need a user promotion so users exceeding 10 post get a secondary group with permissions for that forum