I think you are still confused.
Your first receiver is free, no matter if owned or leased.
Your 2nd receiver is $4.99 a month, no matter if owned or leased.
Your 3rd receiver is $4.99 a month, no matter if owned or leased.
Your 4th receiver is $4.99 a month, no matter if owned or leased.
I think that is about as clear as it can be made.
So yes, if you add a 3rd receiver, it will cost you $4.99 a month programming mirror fee. It just so happens that it will be leased. But you'd be charged the very same $4.99 fee for that 3rd receiver if your brother in-law gave you an old owned DirecTivo or you bought one on eBay.
It doesn't matter that it's leased or owned. It's still $4.99 a month. So you're getting worked up over a fee that you'd pay even if you owned the receiver and it's the same fee that has been in place for 14 years.