Sons iPhone seems to have merged with mine

I have my sons account under family sharing. I also have screen time enabled with restrictions. My apple ID photo keeps changing to his. And I have his contacts in my contacts which have basically duplicated my contacts and just changed their names. I do not want all these random contacts in my phone. The weird thing is none of his friends went into my contacts. It duplicated the contacts I had already in my contacts but it added my boss to his contacts lol. It added Grandpa, Nana and Dad even though I have them under Dad, Mom etc. I'm worried if i go and start deleting then it'll delete it from his. But I really would like it to stop doing this. I'm just confused why it keeps changing my photo each time he adds a new apple ID photo.