The official recognition of a dwarf is any adult under 4'10" (147cm) tall. However, the connection with dwarves in fairy tale and mythology has given dwarfs a special place in popular culture and society. Some, like General Tom Thumb, had successful careers upon the stage and in the freak shows; even today many dwarfs with otherwise everyday careers are drawn to the theatre each Christmas for pantomime productions of Snow White.
Mrs Tomysen was a dwarf in the court of Queen Elizabeth I. Little is known about her, except that she appears in the records as having received 2 oz of gilt plate from the queen at Christmas in 1561. Dwarfs often lived as something of a novelty at courts in Europe, Russia and ancient Egypt, with a role somewhere between that of page or lady-in-waiting and jester. Mrs Tomysen (possibly also known as Thomasine of Paris) was only one of a number of dwarfs employed by Queen Elizabeth throughout her life.
Richard and Anne Gibson were dwarfs in the court of Charles I, employed by Queen Henrietta Maria in the 17th century. They are some of the earliest court dwarfs for whom detailed information survives, and were married at the queen's wish. Richard painted miniatures for the king and acted as drawing masters to the Princesses Mary and Anne, the king's grand daughters. His wife bore nine children, five of whom lived and were of normal stature.
I can find no record of Anastasia Borculaski, nor of famous dwarfs who were brother and sister. However, many married couples travelled and performed together, perhaps most notably General Mite and Millie Edwards, and as some forms of dwarfism are genetic it is not unlikely for a brother and sister to share the condition.