My 2 cents worth moral support if it helps (also read last 100 posts in crimnal Law / Family Law Forum tomorrow as you have one days time to prepare your act)-
Every time you go to CAW Cell, call 100 no. and inform them that you are going there to attend as per the request of the IO (mention name of the IO). (otherwise they may frame you by saying you were there to intimidate the girl i.e. your already abala wife / FIL).
[Go there with (good quality) audio recorder hidden at your waist level so that mic is not obstructed record the sweet talks IO does with you]
Always be polite. Say you are a harassed husband and don't know what is going on and need help etc. Hint to the IO that you know the law and are being helped by competent lawyers and that if she/he abuses the law you will complain against her in writing.
If other members of your family are involved, they do not need to present themselves before CAW Cell as it is voluntary and is basically reconciliatory proceedings between husband and wife. If IO asks where they are, tell her that they are not well and that is the end of the matter. If she insists, tell her that these proceedings are voluntary as per HC.
Rest, play it by the ear. Remember that FIR will not happen before giving you an opportunity to talk to the higher officials.
My suggestion would be that CAW cell is a waste of time mostly but if your FIL and wife are stupid then it is a good opportunity for you to understand their strategy and then get prepared for the same. Mostly it has become a place to fine tune allegations and close any loop holes in the same. After this you will not get any time to talk to them like that J