Exchange 2013 rule to blocking add new device

Hi,

I need solution to blocking additional user mobile devices, but not block or quarantine existing user mobile devices that has connected to Exchange by using Active-Sync device.

I have followed as article below, but this impacted to existing all user mobile devices.

https://www.cgoosen.com/2012/11/controlling-activesync-device-access-on-exchange-2013/

https://practical365.com/exchange-server/preventing-new-activesync-device-types-from-connecting-to-exchange-server-2010/

Is it possible to block only new mobile device that will be add by users, but still keep existing all connected devices?