Dear Sheri,
It wouldn’t be anything more than speculation on my part, as to how they became an Adkins’. If they were listed as Edward’s only once, that may have been the census takers, mistake. But it is more probable that they lived and worked on the Adkins plantation and therefore took the land owners name. I don’t know the personal relationship that the brother’s had with Henry, but it must have been a close one to remain after the mother past. I’m not saying that they were owned, just that they belonged to or was a part of the household. It was a very common practice back then.
As for any formal adoption, and/or any paperwork involved, you’d need to check with the county courthouse for any documents that they have pertaining to the as Edward’s and/or Adkins (some even took their mother’s maiden) Surnames, you’d need to check records all of those. Including Wills. If the courthouse burned at any point, records may be few and far between. Newspapers are a vast wealth of misinformation, but its worth a look. Check all legal documents and land records, they may hold the key that you’re looking for.
I do wish you great success and hope you’ll continue to share your findings.
Thanks for your comment and Welcome to the Family.
Merry Christmas and Warm wishes for 2011,
Sheila Jean Adkins Metcalf