Some of the Marlow sons did carry the name Wilburn/Welborn. As Nancy seems to have died before 1810 census, then a Johnson could be a 2nd wife.
The 1810 census shows no female her age living in the James Marlow household, but there was one in the 1800 census. By 1820 an older woman is living there again. So I am 'assuming' that he remarried and she was the mother to the last two-three children born into this family.
Some of the Marlow sons did carry the name Wilburn/Welborn. As Nancy seems to have died before 1810 census, then a Johnson could be a 2nd wife.
The 1810 census shows no female her age living in the James Marlow household, but there was one in the 1800 census. By 1820 an older woman is living there again. So I am 'assuming' that he remarried and she was the mother to the last two-three children born into this family.