One the son of the other, both with the given name John, one known as John BRITTEN, and the other named John BR*N.  The following is intended to clear-up confusion between the John(s).  

The probate for John states his minor heirs, but when he died is still uncertain (at least for me).  Given "aged about sixteen years" for George, the probate date is 1843.

From this list, it appears that Grtgm Catharine Hensley BRITTEN nursed her children until each could walk and talk, then was pregnant again.

Since John and Catharine were married in 1822 (see link above), then they most likely had two older children, one born in 1823 and one in 1825, and one of them died.

The, now, amended list for 1843: 
 
John BRITTEN 
c. female unkn, age ~18 to ~20 in 1843  
.....(or ~15 ~17 in 1840)  (or ~25 ~27 in 1850)  (and ~35 ~37 in 1860), 
probably the older sister found in the 1840 census, below  
c. George W BRITAIN, age ~16  
.....(or ~23 in 1850)  (and ~33 in 1860)  (and ~43 in 1870)  
c. Lafayette BRITAIN, age ~14  
.....(or 21 in 1850)  
c. Thomas J. BRITAIN, age ~12  
.....(or 19 in 1850)  
c. James M. BRITAIN, age ~10  
.....(or 17 in 1850)  
c. Hugh BRITAIN, age ~8, born ~ 1835.

Also, Catharine most likely died in childbirth (along with their eighth child) in 1837.  There is not a John Tyler in any records for John BRITTEN!

Before adding more records, please note that "minor heir" does not mean "child of."   And note, when The Probate Court of Greene County, MO, made the decisions regarding where these heirs should live, specifically in 1843, does not mean that John died in 1843.  It could actually have taken up to several years to discover (receive the information) that John had died.  We also do not know where John died (via this page, anyway).

Now the amended list for 1848: 
 
John BRITTEN 
c. unkn, age ~25 in 1848  
.....(or ~27 in 1850)  (and ~37 in 1860),  probably named John or William  
c. unkn, age ~23 in 1848  
.....(or ~25 in 1850)  (and ~35 in 1860),  probably named William or John  
c. George W BRITAIN, age ~21 in 1848  
.....(or ~13 in 1840) 
.....(or ~23 in 1850)  (and ~33 in 1860)  (and ~43 in 1870)  
c. Marcus Lafayette BRITAIN/BRITTON, over age of 14, ~19 in 1848  
.....(or 21 in 1850)  
c. Thomas Jefferson BRITAIN/BRITTON, over age of 14, ~17 in 1848,"a poor child"  
.....(or 19 in 1850)  
c. James Madison BRITAIN/BRITTON, age over age of 14, ~15 in 1848  
.....(or 17 in 1850)  
c. the estate of Hugh L. W BRITAIN/BRITTON, ~13 in 1848, 
.....and living with George W BRITAIN in 1860.

From the list above (specifically the first line under George W BRITAIN), 
it appears that John BRITTEN died ~1840. 
 
The 1840 year is most likely per a biography, and a loose page (also published).  
 
We know that John was living, yet Catharine was not present, 
during the 1840 MO Greene Co. Federal Census: 
And, we also know there was a female (a sister probably older than George W).

MO Greene Co. 1840 Federal Census Typed

>1840a   
1840-mo-greene-co-census-typed.jpg  
REF:  "on image"  
RES:  TN Library Research Services

Yet another loose page suggests John’s MO property was still taxed under his name in 1842. 
 
And, I wonder about the location of this property.  Was it a Methodist Meeting House location?

From the above, we know that John owned property in MO by 1833. 
This furthers the idea that his last sale to William BREEDEN, 1832 Jan 10, was probably when he and Catharine started off to MO. 
 
I suggest that John went to MO in 1830 (either in preparation for the move or as a Methodist Circuit Rider (which I still think has research merit). 
 
Wonder why the biography for George W states that his father moved in 1836?  Could this be a move to Greene Co., from another county, rather than into the state?  Then next to Bates Co.  Sure could use some details following this clue for place of burial: 

Where is Forsythe, MO?

>1840b   
1840-mo-question-co-for-forsythe.jpg  
REF:  Peddicord  
RES:  on image

John's place of death was probably on a trip back from Greene Co., TN (not MO) as unclarified in the edited version of the biography (linked above).  (Wonder if corrections to the biographies were ever published?)  
 

There is more, of course. 
Please let me know if I've taken a wrong turn or two or so, 
and thanks for taking the time to compare your records. 
 
Sincerely, 
B.GaiL  
2008 Jan