Batch size for equipment profile

Trying to work my way around this software.  The field for batch size volume asks for volume into fermenter.  Me and two buddies brew 15 gallon batches and ferment into our own 5 gallon fermenters.  Im assuming to leave this at 15 gallons for proper calculations.  Seems like a dumb question but pretty new at this.  So adding to this for fermenter loss would be have to add(combine) our individual losses to calculate that properly?

I have many more questions....

Thanks

yes, the software needs to know the entirety of what's brewing, and getting "lost" along the way, if that loss is known.  As you gradually and more accurately take better measurements of each input and output, and enter that into BSmith for the next brew, the forecast calculations get better, and you gradually "dial in" on what your system can accomplish during a "typical" brew. 

In your case, you may want to maintain a "master" recipe of the 15-gallon size, and each of you have your own "related" recipe to track Starter, Fermentation, and other unique factors you do differently. 

Thank you for the advice..on both topics.  Much appreciated