498-a should one compromise after suffering domestic violenc

What can be the course of action according to law in such cases ?
Take: Continue with IPC sections cases till their logical end.

Should we need to file a case of domestic violence separatly?
Take: If she suffered domestic violence and want to multiply cases and have means then may file another complaint case using sections of DV Act.

Should my sister claim for maintenance charges for herself  her two yr old child and 7 month fetus in her womb ?
Take: If she is not able to take care of herself from any self generated income then she may file either or both i.e. civil and or criminal part of maintenance cases.

If yes what is the appropriate time for doing so?
Take: The time to file it when she is not able to take care of self and child and is destitute lady.

What are the grounds on which maintenance charges are decided?
Take: Status of parties before - at the time and during marriage, earning capacity of respective parties, education of respective parties, income of defendant husband, needs of party seeking so and so maintenance are some of the basic factors to decide the same.

Observation:
Kindly donot use UPPER CASE while writing in public forums, it denote as if you are  shouting at us for no fault of ours.

Apart from the advise of the Tejobsindia.  You sister can file maintenance case u/s 125 CRPC and she can also claim maintenance in petition filed by her husband.  She can claim her share along with her children in the ancestral properties of your husband.

BETTTER TAKE DIVORCE,,, IF U WANT MONEY THAN THROUGH UR SISTER U CAN DEMAND ,,,, STUPID