Original sentence: By February 1990, 790,000 "Estonian citizens" as well as about 60,000 applicants for citizenship had been registered.In 1989 independence activists started registering people  whom they considered to be Estonian citizens by birth according to the jus sanguinis principle, i.In election in February 1990, registered citizenship claimants elected 499 delegates to the Congress from 31 different political parties.The new Constitution, approved by referendum in June 1992, enabled the election of a new parliament in September 1992, based on restrictive citizenship laws that disenfranchised a third of Estonian population.the people who held Estonian citizenship in June 1940 (the end of Estonian independence) and their descendants
Edited sentence: In 1989 independence activists started registering the people who held Estonian citizenship in June 1940 (when the country was occupied by the USSR) and their descendants, who were Estonian citizens by birth by the jus sanguinis principle  By February 1990, 790,000 Estonian citizens as well as about 60,000 applicants for citizenship had been registered.In election in February 1990, registered citizens elected 499 delegates to the Congress from 31 different political parties.The new Constitution, approved by referendum in June 1992, enabled the election of a new parliament in September 1992