> Think of all the title deeds, utility maps and everything that you need surveyors for.

All you need for this is to know whether the existing number corresponds to the old system or the new system and a piece of code that can convert from one to the other.

Well, the old number is 35 feet south of a medium sized pine tree and the new number is 45.1234567, if you can solve for the code we can put Esri out of business.