If the buyer is a Giga's shareholder, he would need someone else who is not to sign the affidavit and figure as another.
[edit:] but there is not any reason why the same person could not have more than one GLBSE account and so reclaim them with a single affidavit.

That's a bit elaborate, but I am not selling at 50%+ discount for nothing.
About following up with cooperation by email if needed, no problem on my side (even to state anything in the name of anyone).

Only problem is about the wallet that I used for my GLBSE transactions: I am not ready to give it away since the situation with other issuers of shares that I own(ed?) is still fluid. So we should figure something about this. In the past I sent back significant wrong payments that I received from 2 respected members (provable), so my word that I will forward to the buyer any payment for his bonds until he change the address may be enough, otherwise we can think about a fix.