Weddingbee boards

My FBIL is awesome when it comes to hanging out and having a fun time, but in every other facet of friendship/brotherhood he is a major fail.  Let me illustrate...

1. He was originally a groomsman because FI wanted his twin sister to be his "best woman".  FBIL (who is 26) litterally threw a hissy fit (pouting, complaining, feeling sorry for himself, putting down his sister, crying) because it was his "only chance to be a Best Man".  FI, being the thoughtful big brother that he is decided to make his sister AND brother "Best People".  FBIL was happy. 

2. We asked FBIL to help us with invitations by writing our the wording for the invitation so that we could use his artistic writing style on the invitations.  We were going to use a copy of his write-out to make a stamp or print out.  I sent FBIL the wording 3 weeks in advance.  Sent him reminders.  2 days before he was supposed to get it back to us he told us he had not had enough time and he did not do it.  We were frustrated, but did not blame him and moved on with the back-up plan. 

3. FI asked FBIL to go suit shopping with him durring my bridal shower.  The morning of the bridal shower, FBIL asked if we could go to a matinee that afternoon (ie, during the shower).  We told him no, we had the bridal shower and suit shopping.  FBIL decided he was too "busy" and went home.  He never offered another time to go suit shopping with FI and told us "don't worry, I would rather find my suit on my own".  He was not supposed to be shopping for HIS suit, the purpose was to shop for his BROTHER'S wedding suit. 

4. FBIL did not throw, or even attempt to plan, a bachelor party for FI.  FI's friend ended up doing it instead. 

So far, my FI's brother/"best man" has failed at everything we have asked him to do.  Including the things he asked us if he could do.  I feel like I should send him a personal e-mail letting him know that he is majorly letting down his brother.  FI does not talk to him about it because it is just accepted in the family that FBIL does not do anything for anyone but himself. Should I let him know what his duties are so that he can acctually BE the "Best Man" or should I stay out and just let FBIL continue to let FI down?  Has anyone else experienced this type of thing?  What did you do?