Call your local Realtor in your area who can give you 1 on 1 attention...Sounds like you did more than just add a few light bulbs. The laws in every state are differant concerning improvements, additions, painting, etc.... more
The real way, if challenged, is to get a market value appraisal based on comps from that date.
Getting comps from us (realtors) isn't always well received so one from an appraiser from that time period (they can back date) would be your best bet.
yes -- they do differ -- market value appraisal v. purchase appraisal.... more