STYLETHREAD -- LET'S TALK SHOP!

hey girls,
i will try to make this as short as possible....
about a year ago, my 15yrold sister in law started "dating" this guy in her H.S. well, to make a long story short, they broke up but during the time they dated, he spent a lot of time at my in-laws' house and became very close to them, b/c his home life is awful. his mom is in jail and his dad is an acholic and abused him. so....one nite sometime in september...it got really bad and John called the police b/c his dad was drunk and he and his 2 sisters were scared. (however, between the months that my SIL and him broke up, he got in a lot of trouble too, w/drugs and skipping school, etc.) so...the social worker said if he got in trouble again he would go to prison (or wherever minors go). he was told he could give them names of who he wanted to live w/ b/c obviously he couldn't go back home. well, he wrote down my in-laws names and he has been living w/them since sept.
he is doing really well now, going to church w/them, making good grades, planning on going to college and my MIL has full guardianship over him and may one day adopt him.
ok, now to the question. my Brother in law is getting married this may and john will be in the wedding. my MIL cannot figure out how to describe what he is for the programs...he's not a brother but he's more than a friend. we need to figure out a happy medium that's short and sweet.
so, i was hoping you girls could brainstorm and thing of a way to describe him for the programs, their website, the paper, etc.
thanks for taking the time to read this. i know my MIL will greatly appreciate it.
(btw, his two sisters are now living w/the church youth minister and his wife and they are doing great.)
thanks so much! jj