From "Beyond the Law" by Emmett Dalton, 1918

In 1918, in his book "Beyond the Law", Emmett Dalton listed the 15 children in chronological order, but he doesn't list anyone named Bea or Elizabeth:

Our family was a large one, fifteen in all – ten boys and five girls. Seven, including myself, are now living, as is our mother...."

Our family, besides our parents, consisted of Ben, now a farmer in Oklahoma; Cole, now living in New Mexico; Louis, who is dead; Littleton, still a ranchman in California; Lelia, who is dead; Frank, who was killed while serving as a United States marshal; Gratton, who was killed in the Coffeyville, Kansas, raid; William, a stock raiser in California, now dead; Eva, alive; Robert, who was also killed in Coffeyville; myself; Leona, also alive; Nammie, dead; and finally the twins Simon and Adeline, of whom Simon is still alive.

Emmett's list of siblings with birth dates

1. Ben (1852), alive
2. Cole (1853), alive
3. Louis (1855) * died young, exact birth date unknown
... * (this is where Bea, born 1856, would be, were she a daughter, but that would make 16 children)
4. Littleton (1857), alive
5. Lelia (1858) * died young, exact birth and death date unknown
6. Frank (1859), dead
7. Gratton (1861), dead
8. William (1863), dead
9. Eva (1867), alive
10. Robert (1869), dead
11. Emmett (1871), alive
12. Leona (1875), alive
13. Nammie (1876), dead
14. Simon (1878), alive
15. Adeline (1878) * died age one year, a twin to Simon

* The "Trusted" label on Emmett's data should be tempered with the knowledge that Emmett embellished a number of facts in his book, but his list of children matches perfectly with the known facts, with the exception of Lelia, about whom nothing is known other than stories from Dalton family relatives and researchers who say she died young.