Here is some information I was able to uncover:
husband: Russell Tomlinson Sullivan (1789 - 08 Nov 1849)
wife: Peggy Isabella Pugh (1795 - 01 Mar 1857)
-> Russell Tomlinson Sullivan
father: Russell Sullivan (1760- 21 Aug 1805)
mother: Rachel Tomlinson (1765 - 21 Aug 1805)
uncle: Owen Sullivan (1759 - 11 Nov 1838)
--> Russell Sullivan
father: John Sullivan Jr (17 Sep 1737 - 1785)
mother: Sarah Seay (1740 - ?)
---> John Sullivan Jr
father: Morris Sullivan (1698 - 1739)
mother: Doniah Butts (? - 1749)
----> Morris Sullivan
father: John Thomas O'Sullivan (1637 - 15 Jul 1698)
mother: Sarah Gore (25 Mar 1653 - 1679)
-----> John Thomas O'Sullivan
father: Owen Donel O'Sullivan (1599 - 15 Jul 1698)
mother: Joann Elizabeth Brown (1613 - 1637) *died in childbirth
------> Owen Donel O'Sullivan
father: Owen O'Sullivan (1560 - 31 Aug 1616)
mother: Helena Butler (1575 - 1616)
-------> Owen O'Sullivan
father: Owen O'Sullivan (1540 - 1594) *born Dunboy Castle, Munster, Ireland
mother: Helena Barry (1549 - ?)
--------> Owen O'Sullivan
father: Dermond O'Sullivan (1520 - 1549) *born Dunboy Castle, Munster, Ireland
mother: Lady Julia MacCarthy Reagh (1520 - 1580)
---------> Lady Julia MacCarthy Reagh
gets a bit fuzzy around this point but traces to Lord Donal MacCarthy, Lord of Carberry, Ireland.
As for offspring of Dempsey Sullivan, I have found no leads as of yet.