wow and sad - i think she has other issues (may be a previous bf, forced marriage, health issue etc.) otherwise
this can't happen even if she hates your parents and wants a seperate house.
whatever be the reason, getting rid of her is not going to be easy unless she/herparents agree to MCD of course
with a settlement money. if she merely demands a separate residence, no chance of a D.
if both are so incompatible and if your latest posting is true, sincere advice is to involve elders to discuss and decide
wheter to continue or not. get that professional counseling done also. convince her to do this with 'love'.
if your brother continues half heartededly, they will make it more complicated. one thing is the opp party
may listen to you only if you shed some tears and play the victim.
if once she demanded money to move out, then i can tell she has no hassles moving out but is holding on for any reason other than a honest marriage.
if she refuses to come close to your brother - that is also a cruetly (not discharging marital obligations) but for that
i think there is a long time limit not a few months, pls ask your lawyer.
demanding money, then denying all this is quite common. They are simply doing drama. they want to be nice/good infront of the society, the so called ladki waale victims.
Finally they will blame your brother for ruining a 'girls' life, and try to extort money as their 'rightful' gain.
check their background - financial ,are they well to do, in debts, are the frequent court visitors etc.