Amph, 1Referee If some trustees turn against you, the others will still protect your funds. For example, an encoded passphrase can be split between mom, dad, wife, best friend. Even if dad, wife and best friend conspire against you, mom will still hold defense (by not giving them her part of the passphrase) 
// I've added this to FAQ section in initial post
Raimonn, RustyNomad You can send copies of the same piece to multiple trustees using a "split" technique:
Everybody useful suggestions, thanks! What are the other problems you can think of?
// I've added this to FAQ section in initial postRaimonn, RustyNomad You can send copies of the same piece to multiple trustees using a "split" technique:
- Split the passphrase in 2 pieces
- Send the 1st piece to mom and wife
- Send the 2nd piece to dad and best friend
Everybody useful suggestions, thanks! What are the other problems you can think of?
That explains it all. Then again, doomthinkers will say; what if the last person gets forced by the others to turn in its part of the passphrase? It's not unlikely for something like that to happen. Especially when the price of Bitcoin is going through the roof at some point.