Pre 1800's Burke Tax has a lot more Martin's on it just in Gunpowder Creek area. How any of them are related we don't know. We again could have more than one martin family living in same area. There were other Martins closer to the Lincoln line too.
I believe Isaac Martin of Wilkes died in Wilkes.He has a will and His family in general left several wills. They are posted on here. Cant remember if its the Martin Board or Wilkes board. Its been a while. There are 2 different Martin families in Wilkes. They lived close to each other and many have gotten them confused. Benj, Zadock and Asa Martin (3 brothers)line in Wilkes came from Rowan and said to have originated from Maryland. Benj and Zadock died in Wilkes and Asa said to have died in Rowan. Isaac Martin of Wilkes came from VA. If you go and look at Martin Wills in Wilkes you will find 2 different Benj Martin Wills. One is Isaac's line and one is the Benj/Zadock line. The Will posted (I think dated 1808) for Benj Martin with a wife Mary, daughter Charlotte and grandson Enos Anderson, This is the Benj/Zadock line not Isaac's. Benj Martin's daughter Charlotte was first married to George Anderson and then Thomas Cook. This family has ties to my Wilkes family and they have nothing to do with Burke that I am aware of. Benj and Zadock's brother Asa was said by others to be going back and forth from Rowan to Stokes but I can not say this is accurate info. I only know they were in Rowan.
Martin is a very common surname so it's very easy to see why some researchers might start mixing them up and they may not be related. Many with the same first names too. People then post info as gospel with no proof and it gets repeated over and over. just like My Martin's. There is so much false info out there on the Martin/Shell connections.
There is no proof found to date that any Isaac Martin died in Lincoln in 1820. This is just word of mouth at this point. Isaac sold ALL his land in Burke and WE Martins who never left Burke/Caldwell had his land. Isaac may have given his family cash and died with nothing. If this is the case there will be no estate record and no way to prove Isaac's children.