As there is no my tree and no your tree, but only one tree. Its no difference between close relatives and unconnected people.
If you find a wrong entry you can go to the profile, click Edit and correct it. As change description or in the research notes and with sources you should explain, why your information is better or more correct than the replaced information.
If the profile is write protected due to privacy reasons, you need to communicate with the profile managers to convince them. If you are a close connected person, you can ask to get onto the trusted list.
Edit: I don't want to accuse you of anything or make any assumptions. I'm just saying as an example: If someone argues that they are a relative and the entry is wrong, that's not convincing. It is better to be able to prove your own correction with a reference or an image.
