Renowned singer Sir Elton John and partner David Furnish are planningto give a little brother or sister to their surrogate son Zachary by this year end, according toreports. One of the most successful English singers of all time, Elton, has already started thepreparation to extend his family, Mirror online reported. "The wheels are in motion. Davidand Elton have never hidden their desire to extend their family, and believe the time is rightfor another child. By the end of this year, or the beginning of next year, there will be a fourthmember of the John-Furnish clan. They are incredibly excited and loving every minute ofparenthood," sources said. Though, till now the partners have not done any genetic test onZachary to find out which one of them is the biological father of the child but now they havedecided to go for it so that the next child will be fathered by the one who missed out last time.