I like that you want to give the games away and not want to delete them.
If you are unsure as a key is still working then i advice the "Ninja Retreat" group because at public GA's the people must not accept a deletion of the Ga if the sended key is not ok. So maybe you are forced to buy keys to replace that ones then OR get a "not recieved" entry and after a bunch of them a punishment from the support.
At the NR group the people accept the fact of deletions with enterng the group (i am sure you find the group at the group recruit threads).

Why = only to sort out the baddest apples Not directed at the level only the % of people that break the GA rules and make trouble/work for the giver direct before the start ;o)

To say it clear:
It is complete your decission how you handle your GA's.