Nope, you cant do that either, as accounts created using a promo-code can not be merged for 12 months.
Also, if paying by credit-card, you might run into the dreaded 'credit-card already is system' error.
If I were you, I'd forget the promo-code and just pay the full renewal, it's still damn good value. Anything else is really going against the spirit of what promo-codes were created for.
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