I do not combine
Caroline and
Carolyn, because I think most Americans do pronounce them differently. However, in my experience most Americans do use the "lynn" pronunciation for the last syllable of
Madeline.
I put
Devon in with
Devin because I think that's what the majority do, even though I know many African-Americans will pronounce
Devon as "deh-VON".
the -iya and -iyah names are hard at the moment. I personally put Miya with
Mia, and Miah with
Maya, and hope that evens things out. :)
I keep
Ciara separate from both
Sierra and
Kiera, because I think that's one where it's impossible to estimate how many should go where. I also keep
Kyra separate from
Kiera, because in my experience most Kyras have pronounced their names with the "eye" sound in the first syllable, in spite of the opposite example of
Kyra Sedgwick.
As I said already, I don't throw in
Alivia and Alivya with
Olivia, but a provide a note about that at the top of my list explaining what the result would be if you combined those.