If someone delivers a dump truck load of toxic waste to your house - do you sign for it too, even if you did not order it????? I was recently asked that question when dealing with a "friend" whom I would LOVE TO DIVORCE.
It seems to me that you are taking the BB Diamond too literal. Use it as a guideline instead and my suggestion would be to use the square in a square pattern. On point it resembles what you are after and the fabrics tell the rest of the story.
As for the "friend" - No is a perfectly good answer. Some people revel in negativity and some (like my nag) would suck the joy out of Ghandi. As hard as this may be for you to hear: None of this is happening without your permission. SO finish the quilt the way you want to see it done, give her a discount on the fabric, hand it off to her son with a glad heart, and don't get roped into another adventure.
If you start to waffle send me a pm. I'll help you out!