I reader provided an interesting and helpful comment in response to the last post:
. . . Apparently there is a cemetery record for Lucy T. Cross in Maple Hill cemetery, now in Madison county showing that she died in November of 1873. I’ve only seen this on and index.
I feel confident that Lazarus Vann was not Lucy’s father. Lucy Tuberville Phipps appears to have been born no later than 1835, her sister Emily was born around 1819, and her brother Robert was born around 1820. Martha married John Richie Inman in 1837, then Lazarus Vann in 1839. Both of these marriages happened after Martha’s children were born.