[Disgruntled Head of C-3PO]

I am having a hard time figuring out Access Control with an Airport Extreme basestation.

I do now want to use any encryption just to allow certain computers with MAC addresses to connect using MAC address filtering.

I know how to add the first computer: Access Control then the + sign then click "This computer".

Now the tricky part.

If I want to add another computer after that point I can't do it by "Adding this computer" because it is already not letting me on the network.

The only way to do it seems to be to type it in manually.

Any way to temporarily turn it off withough deleting the address's added?