Can the case be maintainable at consumerforum if filed by y

Situation:  X and Y family members jointly bought underconstruction residential unit from a builder. X died intestate..his 50% share (self acquired Property) got to be decided by Civil Court among legal heirs and other claimants who are disputing the X's share. 

There is a delay in completion of the project by three years already by builder resulting fiscal setback to Y. The builder is defaulter for interest and penalty on delayed possession.  

Please advise on A),  B) and C)  

A) Can the case be maintainable at Consumer Forum if filed by Y only against the builder in Consumer Forum before the pendency of matter gets resolved among the legal heirs of X share in court? 

B) Can the legal heirs of X's share be arrayed  as parties at Consumer Forum in running case of Y at Consumer Forum at later stages ? 

C) If Y case is decided at Consumer Forum before legal heirs of X's 50% share are decided by civil court then 

will Y be eligible for the interest and compensation for 50% only ...                                                          or 

another case has to be filed by legal heirs of X's 50% share at consumer forum to get their  interest and compensation from builder?                                           or 

the verdict of interest and compensation be applicable for 100 % share?