Hi Rosa! May have a little help for you. And maybe another sibling.
Have you checked out the Family Search Texas Death certificates, which have online images of Texas death certificate 1890-1976; actually, Texas only required death certificates beginning in 1903, and the law wasn't strictly enforced until much later (like 1910 onward, depending on the county). I will give you the website here in a minute, but let me tell you what I found first.
Found Mollie Davis Roberts' death certicate from 1934 in Falls Co. Seems like Falls County was the "home county" for the family. Also found W.H., and the others you already know about. Now the ones you asked about (and more!).
Lee O. is listed a Leo. He dies in 1945 in a hospital in Bell Co. His regular residence, however is Fall Co. DOB is Jan. 1, 1897. The weird thing is that his parents are listed as J.B. Roberts and Mary Dooley. The informant is listed as the hospital records, so there could be some error? He's listed as single.
Then there's Ada, except her death certificate has it as Ida. It's Listed as Ida Ann Ford, parents Duttley Roberts and Mollie Davis. She's born 1883 and d. in 1959 in Waco, McLennan Co. TX. Informant on the death certificate is Lou Genia Ford. Burial was at Greenwood Cemetery.
Found nothing on Jessie, (except a male that didn't match). Perhaps she lived past 1978 and therefore didn't appear on the database. Or maybe the parents weren't listed (that was one of my search parameters).
So now, who is Minnie? I found Minnie Mitchell, father is Duddlie Roberts, Mother is Mollie Davis, b. 1891 in NC, died 1964 in Falls Co. informant was Geneva McCullough. Burial was at Fall Co. Cemetery. I checked the cemetery listing at Falls Co. US Genweb site: http://www.txgenweb6.org/txfalls/FallsCountyCemetery_2005.htmhttp://www.txgenweb6.org/txfalls/FallsCountyCemetery_2005.htm And Minnie is not listed, but there is a reference to Geneva Mitchell.
Okay, so maybe that helps a little. The Family Search site is http://search.labs.familysearch.org/recordsearch/start.html?..#p=homehttp://search.labs.familysearch.org/recordsearch/start.html?..#p=home scrol ldown and click on Canada, US Mexico; then scroll down to Texas death certificates 1890-1976 (the other Texas one doesn't have as much info). If you have trouble with the database, post here and I'll give you the url for whatever you can't find.