Auto-tuplets (sub-category)

Sub-category about twin siblings who can merge and/or split-up. Individually can get blurry depending on how they integrate and their history can make their discovery messy. Perhaps they were born merged and discovered later in life that they can be their own twin(s) for a period, or perhaps they were born as several children who have been able to combine for as long as they remember and share several different names. Perhaps something in between or perhaps this simply happens to apply to some people foreign to our society.