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If you have 戶口本 which contains both your name and your parents' names, just bring this 戶口本 to the 公證處 to do the 戶口本公證. This is the ideal secondary evidence for your birth certificate and the relationship between you and your parents. If you do not hae such 戶口本, you may find some other evidences such as your registration on the elementary school or high school which should have your parents' names and your birth date.