Using an MTH, DCS Handheld Remote and also Wifi

Thanks for reply.  I had been using DCS for years with one TIU and handheld, two lionel bricks, and four power districts.  I have 8 MTH  engines in the system.  My handheld started to fail so I invested in the new wifi.  Not wanting to totally depend on WIFI, I also got a new handheld.  I do realize that the handheld and wifi do  not mirror each other.  But I tried to get to understand things like deleting an engine in the wifi but keeping it in the handheld;  Just trying to learn to understand the relationship.  But I wonder if I messed something up.  Is there any way to damage a TIU in attempts to add or delete or reset various things.  I always assumed that "factory reset" where ever I use it would bring everything back to square one.  I will   take your suggestions about better engine housekeeping .   I had successfully first entered all my engines into the handheld and then having the wifi find them.  And they all worked.  But at some point an engine on the wifi got on the inactive list and I could not get it to go active.  I want to start over using your suggestions.   But first, is there a way to learn if my TIU is working perfectly? Phil

You can mirror the address order in the remote and WiFi device (Tablet or phone) by editing the address in either the remote or the WiFi device so all the engines have the same address in both. Addresses are NOT stored in the TIU. Lionel stores it's addresses in the legacy base but NOT MTH! That is one of the better things about the DCS System. Yo can use any combination of devices and remotes at the same time. This si one reason I have several remotes with only SOME engines in as it limits what that person can control. Barry's WiFi book 2nd edition is fantastic.

Engineer Joe had a post to my initial question.  Somehow it disappeared.