Originally Posted by SPIT
Some programs gets a little snippy about crediting you miles if they see another program's FF# printed on the boarding pass.
Like Mileage Plan.
The other day, I had to fax in a copy of my AAdvantage account summary, with its 950-mile balance, to prove to MP that miles for a recent AA flight had not been credited to AA. I think it was because my AA number was on the boarding passes I printed at home before swapping in my AS number at the gate.