I have been having a look at Eliza. I think its likely that some mixing up of information on either Jeremiah or who he married is happening.
You say she married Jeremiah in 1828 (Do you have a Source?) and was married for 10 years...until his death in 1839. But he seems to have been married to Susannah Walsworth from about 1832 and had three children with her before he died...so unless he was married to both women at the same time, something is not adding up.
I found Jeremiah's grave, buried beside Susannah Walsworth. The FAG entry says they married in 1832. Under Susannah's FAG entry it lists two of her children. Lydia Melissa Purdy b. 1833 and Milton Bentley Purdy b. 1839 All of them with headstone images.
https://www.findagrave.com/memorial/38882294/jeremiah-purdy
I found a Census record (1855) for Susannah Purdy, Widowed, who is with her children Lydia Melissa Purdy who was born about 1834, Milton B. Purdy who was born about 1840 and Lucy M. Purdy about 1843. Census record birth dates are very often incorrect. The FAG entry gave earlier birth dates for Lydia 1833 and Milton 1839.
https://www.familysearch.org/ark:/61903/1:1:K6SJ-KWH
Your Eliza Blair Purdy shows up widowed in 1850 with three children, Lucena b. 1831, Sarah b. 1833, and Jeremiah b. 1839.
So I would suggest that there are two Jeremiah Purdy's that you have conflated. Unless there is some other explanation?