Is there a way to add a second segment in Natural Accounts in Book Controls window?

Hi Cummunity,

We need to know if there is a way to set up a new flexfield in the Tab Natural Accounts of the window Book Controls, in order to input two segment values, for example in Net Book Value Retired:

                                             Gain

Proceeds Of Sale               4200

Cost of Removal               1246

Net Book Value Retired      5600-710

Reval Reverse Retired        1245

At this moment we just input one segment value, but we want to have the option to input two segment values.

Thanks and Best Regards,

Gualberto