My wife’s old phone became obsolete, and I have an iPhone which is not in service, so she put her SIM card into that phone and it’s working for her. The problem is that that iPhone is, like my current phone, a company-provided phone (they never got around to collecting the old one when they upgraded me to a newer version), and they are linked to each other. So that when she deleted a contact from her phone it got deleted from mine, and when she deleted the Favorites from her browser, mine were deleted too.
Question is: is there a way for her to unlink that phone and have it continue to function properly? I’m afraid that some of what makes that phone run altogether is my company-provided Apple account and that if she logged out of that, or something similar, it would cease to work altogether.
I think it depends on how your company configured the phone it issued. The iPhones my company issues are enrolled in the Device Enrollment Program, which gives the employer certain access to and control over the phones. If that’s the case, your options may be limited. You should talk to whoever in your company is responsible for these phones to see if it can be removed from control and whether it’s OK for you to keep it.
In general, if both phones are signed in on the same AppleID, then yes, the contacts and favorites will be synched. I have heard, but cannot confirm (haven’t used an iPhone in years) that if you turn off the Sync function though, it will prevent the changes being rippled to the other device. The following may be helpful in that case -
On your iPad/iPhone, go to Settings app → Tap on your name and picture shown on the top (Apple ID, iCloud, iTunes & App Store) → iCloud and under Apps Using iCloud section, turn-off the switch in front of all the apps for which you do not wish to sync data.
Specifically contacts, browser, and probably just about anything else - although if you use a shared calendar / appointment app, or anything else it’s helpful to share, you may want to preserve it.