Do you know for sure your Quinn's sister married a Mullins??
here is the date of marriage
Marriage Bonds of Duplin Co. N. C. 1749 - 1868 pg. 77
MULLEN, William, Nancy QUINN, 23 Nov. 1803 (b) John x Brock, (w) Wm. Dickson, C. C.

Some believe my Line of Lewis Mullins parents are Wm & Nancy Quinn Mullins, but with the marriage in 1803 and no other children listed for then untill 1809 than i believe that the Lewis & Bridget could be the parents :-)
here is what i have

Descendants of Lewis Mullins

1 Lewis Mullins b: Abt. 1782 in N.CAROLINA d: Aft. 1851 in Ga
+Bridget Layfield b: Abt. 1790
2 Thomas Kinion Mullins b: January 16, 1809 in Newburn,CravenCo.,NC d: December 03, 1886 in Pike Co.,Al.
+Pamelia Brockman d: March 31, 1880 in Pike Co.,Al.
*2nd Wife of Thomas Kinion Mullins:
+Mrs Eliza Battle
2 John Mullins b: July 18, 1812 in Franklin Co.,NC d: May 26, 1895 in Greene Co.,Ga.
+Julia A ?? Mullins
2 Lewis Mullins b: April 27, 1815 in New Bern,Craven,NC. d: June 23, 1868 in Al.
+Catherine Gipson b: February 26, 1819 in Forsyth,Marion,Ga, d: July 10, 1888 in Al. Father: William Gipson Mother: Elizabeth Snellgrove
2 Mary V. Mullins b: Abt. 1822 in Ga
+Sampson Gipson b: Abt. 1809 in SC Father: William Gipson Mother: Elizabeth Snellgrove

Thanks and good luck
CGT