IPhone location switches b/w devices

I have 3 personal iPhones that are all on the same Apple ID yet have individual phone numbers. In settings on Find My under my location I want each phone to use “this device” for its location. However when I choose “this device” in settings it changes all 3 phones location as that phone for their device location as well. This is causing major problems when using Maps for directions as my husband may be in one location and I in another yet when I put in address in maps my phone is showing my location as where he is located because without my knowledge my phone has switched to using his device as my location. I’ve spent hours on the phone with Apple trying to figure why and how to get this to stop. They cannot figure it out even after checking settings throughout each phone. We have used one Apple ID for years yet never had this issue before. We have also experienced phone calls and text showing they are being sent from the opposite phones number/contact. It seems as if our phones are intertwined with each other. Also we can no longer allow share name and photo when making calls or sending texts as it says it isn’t allowed because more than one number is associated with one Apple ID yet we were always able to do this before as long as only that phone number is selected to send and receive messages. It’s frustrating when speaking to an Apple rep who attempts to explain away the issues with answers that I know are incorrect. One Rep told me, regarding the switching of device locations, “well you really don’t use that particular phone much so it shouldn’t really matter “. I want an answer as to why it’s happening and deserve a deeper look into the situation, not an excuse to sweep it under the rug! Nobody at Apple can explain this strange phenomenon yet they claim to be highly concerned with customer privacy and security. There is not a way to escalate this issue to a higher level to actually assess the problem and find resolution? I don’t want to pay for a technology forensic specialist to examine my devices. I paid quite a bit of $ for the devices and Apple should back up their promises of security and privacy and do the examination themselves. Any direction is welcomed.