This name should be spelled Floyd Merble Bachman.
There is much discrepancy in the various Census records with regard to the 'Given' Name(s); plus, spelling, of the of your Grandfather's 'Given' Name(s).
There are only Census that are attached as "Sources"; therefore, it is understandable with regard to the confusion.
- 1910, Census of the United States of America = Merle
- 1930, Census of the United States of America = Merble F.
- 1940, Census of the United States of America = F.M. [ Initials ONLY ]
Are you able to find and attach, Birth; and/or, Death, Registration records that record the actual 'Given' Name(s).
I am not familiar with Records from the State of "Oklahoma" in the "United States of America".
Are such, Birth; and/or, Death, Registration records for the State of "Oklahoma" in the "United States of America" available in "FamilySearch"; or, for that matter, 'On-Line' elsewhere?
You can CERTAINLY "Change" ( ie. correct ), both, the 'Format'; and, the 'Spelling', of the 'Given' Name(s) of your Grandfather; but, I do suggest that, BEFORE you do, you have (or, obtain) the "Sources" or evidence of the Records that record the actual, 'Format'; and, 'Spelling', that you want to change the details to.
That is what "Family Tree" of "FamilySearch" is all about, the most accurate record possible, supported by evidence (ie. "Sources"; or, actual, 'Documents').
I just did a quick "Search"; and, found a "Source" in "FamilySearch" from "FindAGrave", that has an 'Image' of the Headstone of him and his Wife, that you can attach.
And, in "FindAGrave.com"
Please "Note" that the actual 'Date" of "Death" on the "Source" (and, Image) is DIFFERENT to that in "Family Tree" of "FamilySearch"; whereas, you will be pleased to see the spelling of the 'Middle' name on the "Source" (and, Image) = "Merble"; unfortunately, there is ONLY a FIRST 'Initial' and NOT 'Name'.
I hope this helps.