This does show you how these orgs are set up to cover every base.
The next step would be to find someone who has the patience to read the FEC legal stuff, and find out if the MoveOn PAC is allowed to borrow envelopes from any of the other MoveOn entities. Asking the FEC to investigate it is only going to get you a lot of waiting.
Here's the way I see it....MoveOn.org NOT MoveOnPAC is paying the postage because they are the return address so it is a violation for them to send it out!