Question about signed papers regarding custody.?

When my sons father and I split up, he started paying child support...or well was supposed to. In our papers, they also attached visitation papers incase we cannot get along and want to go by them. My sons father rarely goes by the papers and decided he wants something written because he has warrants out for him and thinks I will call the cops if he doesn't bring Caleb home by a certain time...so he decided to write a note saying he will have Caleb every other weekend from 6pm Friday thru 6pm Sunday. Will this paper hold up without it being notarized? Or is this something that we would have to go to the Attorney Generals and actually modify our papers. I don't really know anything about the law...we live in Texas. Any help would be great, thanks!