Why are my contacts syncing with child’s and iMessage conversation deleted through Family Sharing

I recently purchased a iPad for my daughter and set her up with her own Apple ID.

(Note: She has never logged in to my Apple ID on her iPad and I have never logged into her Apple ID on my iPhone.)

I used the Family Sharing functionality to set up her iPad’s Apple ID initially and we are still linked through Family Sharing.

My problem first started when just her contacts were being added to my contacts list (but not mine to hers). But now my iMessage/Text conversation with her Apple ID has been deleted from my phone, it’s not showing in my recently deleted messages so I know that I did not accidentally delete it. Her iPad is on an older version OS and so I cannot see her recently deleted messages but my current theory is that she did delete it from her device.

Why are my child’s contacts being added to my device? Why is it that when my child deletes our conversation history from her iPad the conversation is also deleted from my iPhone? How can I stop this from happening?

Any insight would be appreciated.

Thanks,

Paul