The key to programming a new ID is to turn off bluetooth. Using them in a lashup is personal preference. No harder to troubleshoot a consist if they all have the same ID number, Just put the suspected bad actor on the track by itself. Lionel created that feature to make it easier to set up. Save the two extra IDs for other engines.
Not sure I understand about turning off Bluetooth. You shouldn't have to do that. The Legacy radio and Bluetooth are mutually exclusive. The TMCC/Legacy ID is using an entirely different frequency and channel when communicating with the base, where Bluetooth has its own private comm channel setup.
I own several Legacy Diesels ABA and ABBA units with Bluetooth and I have never turned off that feature to assign or change IDs.