Storage Slips - Can I add an item?

I have all my ol' festive junk on storage slip 11, obviously..
But today I found that I had a Gobbie Gavel laying around and wanted to add it to my slip..
I haven't played in a while so I'm out of touch.. is there no way to merely add an item to a storage slip?
Or do I have to retrieve all the stuff and get another storage slip just to add an item to it? Help!

You can add any individual item to a slip, unless one is already stored on the slip. Trading the slip to the Moogle will show what items you have stored inside it.

Yeah - I realised about 10 minutes after posting this - of course, I could trade my Gobbie Gavel and the slip to the Storage Moogle (at the same time) and he'd insert my gavel into my slip.

EDIT: Forgot to post 'thanks' - Thanks for replying though!