As Stephen says, you must plug the OAT into the ADAHRS. If you have two ADAHRS units, you need to install two OATs. If you don't, you have no redundancy on OAT (which is used for a lot of calculations).
The SkyView screens don't have an OAT connection, so you never run the connection to the screen. If you do want to use an OAT for something other than OAT (cabin temp, firewall temp, etc), you can run it to the EMS module and use it there.