Except as otherwise set forth in these Official Rules, prizes won by a person who is a minor in his or her state, province or country of residence ("Minor") may, in Sponsor's sole discretion, be awarded to his or her parent or legal guardian, and, in the case of prizes that, in Sponsor's sole discretion, require winner verification, that parent or legal guardian will be responsible for completing the verification process and executing all "Prize Claim Documents" (as hereinafter defined) and otherwise complying with all requirements imposed on winners set forth herein. Notwithstanding the foregoing, in the event a Minor is the winner of any prize in which the winner is permitted to travel to, stay at or attend an event, site or destination, such Minor and any guest (as applicable) must be accompanied by his/her parent or legal guardian on such prize and, as applicable, the parent or legal guardian will be considered one (1) of the allotted guests.
(see post 80 for pictures), so they seem to be acceptable.
That doesn't apply to my DM however.
, the rules magically changed about a week later to read 3.5x5. 
Last time I saw that section of the rules, it still says 3.5x5.
- I just bought some pre-stamped post office post cards - which side is which? Is the side with the stamp the front where I put the Disney address, and the empty side the back where I put my info? I have TO: and FROM: on the postcards, but I thought I'd ask here, just to be sure!
