Thank you for your reply and info.
I've researched this line very thoroughly. It is my direct line.
Myrtle & Flora were twins however after that 1900 census, Myrtle vanishes. Not one member of our family ever mentioned her name . . . never . . . ever . . . !! I saw that 1900 census as "a fluke" but by that time, everyone who might have known was long passed away.
Flora was living next door, during 1900 census, with her grandmother, Dora's mother (i.e. Pernecia Piper).
Dora & Ed both died in Michigan but are buried in MO. That death info you sent on "a Dora Simon" (death in 1941) is not my grandmother. She died in 1937. Ed died in 1938.
I have documentation on Dora' marriages to all 3 of her husbands: #1 J.A. Killian/Killion, #2 Charles Good and #3 Edward Simon (my grandfather).
After yrs of "dead-ends/brick-walls", I've pretty much decided that Myrtle Good died at some point right after that 1900 census but probably before 1908 and is buried in "an unmarked grave". I've searched cemeteries in at least 5 counties and found nothing, using several surnames including Good, Killian/Killion, Piper & Simon (also various spellings of Simon) By 1908, my grandparents were living at Purdy, MO. They lived there only a few yrs, then moved to Rocky Comfort, MO. When they became older/ill, they moved to MI but per their request, they are both buried @ Rocky Comfort.