bmi diamond club - Signup bonus not allowed to redeem flights for other persons?

As stated by GoldCircle in http://www.flyertalk.com/forum/11157997-post12.html, I wonder if anyone of you ran into problems by redeeming miles from a signup-bonus account for another person?
I was quite surprised when I read this. I signed up my sister - who exists - in 2008 and have now booked with the signup bonus an award flight for my friend. Ticket is issued, miles are deducted, money is taken from the credit card. Should I be worried?

IIRC the t&c's changed during the duration of the 9000 miles sign up bonus. Some accounts will not have the rule about the account holder being the only person who is allowed to use the bonus miles whilst some accounts will.

I'd be more worried about posting the fact that you booked a ticket for your friend using the miles from an account that doesn't belong to you.

I'd be more worried about posting the fact that you booked a ticket for your friend using the miles from an account that doesn't belong to you.
No worries, I am assigned to my sisters account. All is okay with that.