IPad – remotely control an IPad 9.7 running ios 11.2 with Teamviewer on a MacBook Pro

Yes - make one user account for your iTunes library and a second user account for your wife.

As far as I see, this is no problem at all having two independent user accounts on one system, each using a separate Apple ID to login to the Cloud and iTunes. I tested it on my Mac (10.8) just now using my work Apple ID under a freshly created separate user account and found it to work.

This method has worked since OS X was first developed and it's unlikely to change anytime soon. You can search here for other questions that cover how to share some or all of the songs between separate accounts, but it's always easy to combine things later than it is to start mixed and separate things later.

I'm afraid this is not possible, at least with a non-jailbroken device.

iOS Apps are built as SandBoxes at install time, which means that each App has access only to its own files, and very limited privileges with other of the device's services, such as the phone, sending emails, etc.

Apple states it like this:

For security reasons, iOS places each app (including its preferences and data) in a sandbox at install time. A sandbox is a set of fine-grained controls that limit the app’s access to files, preferences, network resources, hardware, and so on. As part of the sandboxing process, the system installs each app in its own sandbox directory, which acts as the home for the app and its data.

Important: The purpose of a sandbox is to limit the damage that a compromised app can cause to the system. […]