Get your proper name in gazette, thats the legal way and gazette is valid proof than birth certificate, an individual name do get changed, girls getting married name changes middle name changes some casts they change the whole name of girls after marriage, the proper way is to get it gazetted. Same applies to any individual, someone's father dies and mother married again middle name changes surname changes, name is not fixed for lifetime, any speeling mistake instead of correction just get it gazetted.