I still have not made the connection.

As I stated before, my angle is just a working theory at this time. I just can't seem to find the evidence I need. I have an image of the will I took from microfilm. This is a curious document, as is the evidence I have collected. I'm coming at this from the ROSS side, so it may not be of any help to you, but I'll see if I can piece this puzzle together in a way to make sense. Like you say, it does get confusing. Let me give a rundown. It's late though, and I'm away from my database, so will do so from memory the best I can.
 
I can get back to James Monroe Tubbs b. 25 Jul 1854, Tenn easy enough, and am confident to that point. Records show he went by Monroe frequently. I have a census that has a George Boley enumerated in his home and listed as 1/2 brother. An earlier census has Monroe and a brother Isaac Tub in the home of B. F. Boley wife Mary and four Boley sons (1870 in Missouri if I recall correctly). Next door to the Boley family is the Coats family, wife Adaline b. 1849. Tenn. Neither Isaac or James Tubbs death certs supply any details on mother or father. Three of the Boley boys death certs list Mary Ross as mother. Adaline's Coats' death cert lists a Polly Ross as mother. Further, her obit also mentions brothers James and Isaac Tubbs, as well has 1/2 brother B. F. Boley. This really helps to further tie all these folks together. There are some problems with the obit, for example it mentions James even though he had died about 5 years prior. She's in MO, and James moved to Texas and then Oklahoma, so my guess the families were not in touch too often. I also have marriage certs for a Mary Tubbs to B. F. Boley (Caldwell Co. Mo) and Adaline Tubbs to J. Coats both in Missouri before 1870. Adaline's obit further states she came from Tenn to Mo by boat at the age of 9 (would have been 1869), but Isaac was b. Jan 1860, Tenn. I cannot find this family in the 1960 census, and am guessing they must have been on this move at that time. While I feel fairly certain back to this point, from here I need more evidence.

Having established the mother is Mary ROSS, I find a Charles Ross already in Caldwell, Co. Mo. Listed in his home in 1870 is his mother Nancy Ross. Charles Ross made the Caldwell Co. History books, and seems to have been a well know figure in the county during his time there. His ancestry is listed (thankfully), and parents were Martin and Nancy Ross. No mention of siblings however. I can find Mastin (or sometimes Martin) and Nancy in the 1850 census in Cannon, Co. Tenn. The entry is odd, but it lists a daughter Mary Ross and it seems two children William and Adaline *ROSS*. The ages for these Mary and Adaline fit perfectly with the info I've mentioned above. Also, a census that list number of children and number living fits with Mary, and would indicate William probably died prior to the move to Mo. (I've no proof of that). My guess is that Mastin must have died in Tenn, and the family with mother Nancy made the move to Mo, where son and brother Charles Ross had done well for himself. (Again, no proof, just a theory.)

So, somewhere between 1850 and the 1860s, the TUBBS name shows up. I still don't have a connection. This will though, is curious in that TUBB is listed, along with an Adaline and Monroe Ross. This fits the theory that William had died, and Isaac had not yet been born. Another interesting bit is something another research told me (before I even found this document), is that is granddad (LeOrey Tubbs son of James Monroe Tubbs) had told him his granddad's name was Moses. That also fits here. So, it's in the right place, and has several of the right names.

Things I wonder about are did Mary Ross ever marry a Tubbs? Were the children illegitimate Tubbs children? Did they just take on the Tubbs name when they moved to Mo? I've no idea. That's where I'm at. I've been researching about 2 years now, this is my first wall, and has been for most of that time. I'm not really sure what to do to break through. I'm in Mo, and have been told that Smith and Cannon Co. Tenn are hard places to gather info. That folks from there didn't leave much for tracking them down. I sure hope that this family can be connected sometime. It may take a trip to Tenn to find more.