assoicate the same test schedule to all test plans in a proj

i have more then 40 test plans in my project area , and i'm looking for a way to associate the same milestones to all my test plans ,
it's very difficult to enter each and every one of them write the milerstones over and over, and do it again when i have new milestone .
i was consider of using RQMUrlUtilty to GET the test plan , in order to change section regarding the schedule in the generate xml and PUT it back , but the generated xml does not have reference to test schedule ,
any idea will be appreciate

thanks :D