I keep an updated computer list, backed up on flash drive and hard page copy.
I ran into the same trouble with the boss walking in on me and asking how many... I told her that the gun safes were not all full. SHE ASKED HOW MANY GUN SAFES DO YOU HAVE.... had to scale back a bit. Now however, in addition to the serials/accessories and identification info, I also have added who I wish to get the gun should it still be in my collection when it becomes hers.... Pretty sure someone will get a good deal on the ones not named as she said she would sell them all for 5 bucks each...(( Sad to say I believe she would )).
I also have asked a couple friends to step in and guide her through disposal of all guns and gear should I go missing. That information is also on the paper. What is not there is the name of the person I bought or sold the gun to other than their first name and the date/location of sale.