Originally Posted by
timelinex
I absolutely know that I can't get bonus points if I signup to a platinum while I have a gold.
You answered your own question.
Not to mention these are not Corporate cards, they are personal cards for Business Expenses. Your personal credit backs up the charges, not a Corporation.
Also not sure how having Membership Rewards points, which have no cash value, in the same account is a liability concern. I think you're over reacting a little bit.