Individual message background customization for each iPhone user

An update meds to allow each individual in messages to select the message background for their OWN INDIVIDUAL phone.. Everyone that's part of the message having access to change the background for everyone defeats the purpose because everyone wants to choose their own background. So it's constantly getting changed. Defeating the feature purpose. When I change a contact's background in my messages they also are able to change the background in my messages. Makes no sense. I should be able to choose and change my background without their messages background being affected. Vice Versa

[Re-Titled by Moderator]

Original Title: Messages customized Background