Yes! That's not completely tested by me, but all the evidence I have is that when you subscribe at any level you also receive messages at all lower levels.
However, if you look at a lower level you see no indication that a subscription is in place. I think this may confuse people, as someone once complained to me of duplicate messages. It turned out they had an additional subscription at a lower level.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.