How excited I was to read your message!I have been looking for the family of Elizabeth Adcock Coleman for several years now. I have seen this 1850 census listing of the Christian & Elizabeth Coleman household, and I came to the same conclusions you did.Here's what I think:
Elizabeth Adcock (b 1817 VA) is the sister of Joel Adcock (b 1811 VA) and Anderson Adcock (b 1817 VA)and they are the children of this Joseph Adcock found on the 1850 census. This family came from VA and settled in Robertson Co, TN.I have found many Adcocks there in Robertson Co but cannot connect Elizabeth to any others.The question is "who is this Joseph".More than likely he is of the family of the two Adcock brothers who came to TN from VA-John Asa and Pappy Joe.I have no additional info on Joel or Elizabeth.
If you notice on that 1850 census, there is also a Joel Puckett listed in the household.I wonder what his connection to this family is. I have seen several Adcock-Puckett connections (marriages) of this same location/time period and wonder if Elizabeth Adcock's mother was a Puckett.