Talley Ho. The rules are quite clear. You enter mexico with an FMM. After you get a Temporal you keep the TIP. It is valid as long as your immigration status is renewed. You must inform Aduana when you renew. I do not know how this is done. Thousands of expats do this all the time. Some never get a permanente. I don't keep up with a lot of this but that was the rule shortly after they changed in 2012. When I have time I will try and find more info. Part of the problem is that people go to their local Immigration office where the clerks give hem bad information. In HMO there is an office where one can go and get all kinds of help with Federal issues. They can offer tax information and a lot more. I am sure they have these offices all over Mexico. Immigration do not know anything about Aduna, Banjercito and the Hacienda.
Moisheh