@eMSW21 Thanks for the reply! I actually already asked for an extension from BU- they originally had a March 5th deadline but changed it to March 12th for me. I don't think they will move it later.
In terms of the financial aid, I meant the opposite- I was worried if I told Columbia they're my top choice, they'd lower my financial aid. I like the idea of showcasing a larger package from another school, but I don't think I'll hear back from Columbia until I already have to make my decision about BU regardless.