Right of a grandson

A hindu family has 2 brothers (1 married,S1 and 1 unmarried,S2) and 1 married sister,D (marriage in 1995). sister living happily with her husband.

elder brother,(S1) has a small business and has 2 kids ( 1 son,4 yrs and 1 daughter,6 yrs). wife of elder brother (S1W) is not doing in any job. she is a hosewife. both are alive.

younger brother(S2) is in study+self employed

wife of elder brother (S1W)  more oftenly threatens to divorce and file a dowry case against elder brother and his whole family.

their FATHER (F) is in govt. job and MOTHER(M) is housewife (both alive).

grand father(GF) and grand mother(GM) both are deceased.

there is some ancestral property (self acquired by grand father, GF)

there are two more property as houses. both are self acquired by the FATHER(F) himself. one house is in the name of FATHER(F) and other house in the name of MOTHER(M).

my QUESTIONS are ............

1) is there any law 0r some way to protect the family against the dowry case threatening by the wife of elder brother (S1W) before she does so ?

2) is there any right of wife of elder brother (S1W) on behalf of her son ( kid 4 yrs)  for share in the properties  self acquired by the FATHER(F).( her father - in- law )  either before divorce or after divorce.  plz also answer in relation to ancestral property.

3) does the daughter (D) has right to demand her share by her father(F) in his self acquired properties  either her father is alive or deceased.

4) in case there happens a divorce b/w elder brother(S1) and his wife(S1W). what are the liabilities  of husband(S1) on his divorcee wife(S1W) and his kids. 

5) if in future, mother (M) and father (F) wants to write their self acquired properties only to their younger son (S2), will it be LEGAL ? .  if it happens so,  after writing their self acquired properties only to younger son(S2) and both are deceased, will there be any right of elder brother(S1) OR the married daughter(D) for claim in this property.

6) if FATHER(F) and MOTHER(M) both are DECEASED  without declaring their properties, then does the daughter(D) has any claim for share in her father's self acquired property.