Section 903. Necessary defendants

Each of the following persons shall be
  made a party to the action:
    1. Every person having an undivided share, in possession or otherwise,
  in the property, as tenant in fee, for  life,  by  the  curtesy  or  for
  years;
    2. Every person entitled to the reversion, remainder or inheritance of
  an  undivided  share,  after  the  determination  of a particular estate
  therein;
    3. Every person who, by any contingency, is or may become entitled  to
  a  beneficial  interest  in an undivided share in the property, provided
  that where a future estate or interest is limited in any contingency  to
  the  persons  who  shall compose a certain class upon the happening of a
  future event, it shall be sufficient to make parties to the  action  the
  persons  who would have been entitled to such estate or interest if such
  event had happened immediately before the commencement of the action;
    4. Every person having an inchoate right  of  dower  in  an  undivided
  share in the property;
    5.  Every  person having a right of dower in the property, or any part
  thereof, which has not been admeasured; and
    6. An executor or administrator,  where  letters  testamentary  or  of
  administration  have been issued on the estate of the decedent from whom
  the plaintiff's title to the real property is derived, and the action is
  brought within eighteen months after such letters were issued; or  where
  the  person  of  whose  estate  the  executor  or administrator has been
  appointed should, if living, be a party to the action. If no executor or
  administrator has been appointed for the estate of such a  person,  that
  fact must be stated in the complaint.