Diluted ZamZam

Q: Does the Hadith "Zamzam is for the purpose it is drunk for" apply also for a small amount of zamzam which has been mixed with tap water? Also, should we recite the dua "Allaahumma innee assaluka ilman nafia [..]" when drinking such diluted zamzam water? I am asking since I heard that the qualities of zamzam remain even after dilution.

Inheritance

Q: I wanted to ask question regarding inheritance. My father passed away 25 years ago now. My brother and sister have had many disagreements through the years. So for so many years our brother has been maintaining the house and still is and about 20 years ago he bought his own house so no one lives in our family house now. I want to ask that because my brother and sister have disagreements and that my brother has been maintaining the family house by himself and also gave all of our father's debts. Does me or my sister have any right to ask for our share in our father's estate?