Usually there is an Artist relations person who handels thing like that with bigger lines  , i think with smaller ones , you just have to ask the top, also networking and getting to know the people in your industry , you would be surprised who on here have some amazing lines , David Klasfeil , Liz Yu, to out a few lol  and there are other artist on this site that work for different lines that can help "hook you up " although im not comfortable outing anyone who dosent "out themselves"