I could be wrong, I don’t think that you can.

In our environment, we don’t use bin transfers very often, and so I’m not very familiar with the record, but I’ve done a lot of customization in our account. I can tell you that some records in NS are locked. When you’re in edit there isn’t a “Customize” button in the top right corner. Usually, that’s an indication that the record is locked. I poked around in my own account but I have the same issues.

I would search to see if there’s an enhancement to unlock the Bin Transfer record. If it locked, I’d be surprised if you’re the first to ask about it, and so I would expect there to be an enhancement for it. If you can’t find it I’d open a case, if nothing else they’ll definitely be able to find an enhancement if there is one. I do have a hard time seeing a way to add a field if the record is that well and truly locked up.