Three groups of womb twin survivors

There are, I have found, various sub-groups of womb twin survivors. Right at the start, I found three distinct groups,  (I called them M type, C type and D type for want of a better term)  and despite all kinds of analysis, six different lists of questions and examining over a thousand stories, those three groups are persistent, so there must be something in this, mainly because I did not expect it, so I know Im not making it up.

I have reached a tentative conclusion about this, and  so I have made up some user-friendly names for these groups (No one likes to be categorised as a "type" that is so impersonal!)

GEMMY - they were once a fraternal (dizygotic) twin   (After Castor and Pollux, Gemini twins)

CHIRO - sole survivors of a triplet set where two of the triplets were monozygotic twins  (After Chiron, or Kyron or Cheiron, depending on where you look)

MIMI - they were once  a monozygotic (identical) twin  (Two individuals in one, each of them a ME.)

At the very start of this in 2003 I quickly found GEMMY and CHIRO, but MIMI took a while longer and is only coming clear this year.

Now Charles Boklage suggests in his work ( he did some statistical work on the incidence of vanishing twin syndrome in 1990) that most of the twins lost before birth are probably monozygotic (and male, which is interesting: most womb twin survivors who come to me are female.)  That means therefore that there are far more MIMI survivors than there are GEMMY or CHIRO survivors. But my research has not uncovered them yet, for they have not come forward. I wonder why not?