Distribution of property according to the will in parsi zoroastrians

I am a married parsi woman. My unmarried uncle (say Mr. X) made a will naming his 3 brothers and one sister as equal beneficiaries. One of the 3 brothers (say Mr. Y) is also unmarried but has made a will naming me, his niece, as the sole beneficiary. My question is, if this unmarried uncle, Mr. Y expires before Mr. X, then will the assets of Mr. X be divided into 4 parts and will I inherit the Mr. Y’s ¼ share or will the assets be divided into only 3 parts as one beneficiary is already deceased. Also, what if one married beneficiary expires before Mr. X. Then will his share go