Confused about 2FA, Trusted Devices, Device linked to Apple ID
I am having a hard time understanding the relationship on these security features.
First off, I have 2 iPhone, my old one is being used by my son, and also have some other apple devices.
Since I use my apple ID on both iPhone, both appear as trusted devices on my account info. I really want this so if I ever lose any of them, I can use Find My Device.
My problem comes If I try to log in to my account on any laptop (example) and I get the Verification Message on all the trusted devices and sometimes when my son is using the device he accidentally presses de cancel/ignore before I can accept on my iPhone, so I have to retry to log in. It's kind of annoying, and yes I have talked to him about not pressing it, but it happens anyway. Also I am better off if he presses the not allow option, what if it isn't me trying to access the account. Price to pay for security I guess.
TL; DR : So my questions are, can you remove an iPhone (B) from trusted devices so I can get the verification codes just on my other iPhone (A) , and will that iPhone (B) once untrusted still be linked to my apple ID, be able to use Find My Device and be linked to apple ID activation if tried to restored (basically making it useless if stolen) , or must a device be trusted to be linked to my account/find my device? if it's the latter, can you somehow configure then which device recieves the verification codes? Also once untrusted will the iPhone (B) resign or get listed again as trusted for any reason?
iPhone 8 Plus