File partition suit if out of court settlement is not possible. And at least grab that much share you are receiving, rest you can get through court if partition is unequal.

file suit for partition for division of property by metes and bounds 

2) seek injunction restraining sale of property by other legal heirs 

3) contact a local lawyer 

You can file before the court for partition for your share of the property. If the person is failing to mutually partition the property and give you your legal Share.

The share of the property belonging to your father in law is to be divided amongst his sons and daughters. You dont have a right in it. However if they are willing to give you you should file an application in the sub registrar for the property documents.

Regards 

1. You are entitled to 1/4th share of your deceased father in law's property which actually was inherited by your late husband.

2. The certified copy of the property document can be availed from the office of the Registrar and the copy of the balance sheet of the firm can be had from the ROC.

3. If he/they are not willing to give you the due share of the prioperties amicably, file a partition suit claiming your equal 1/4th share of your father in law's properties.

if the issue is not settling amicably, approach the Court for the partition of the property

This is my response to you:

1. Send a legal notice;

2. If he does not respond then you will have to approach court;

3. Still the other co-holder can settle the matter;

4. If he chooses not to then ask the court to pronounce orders;

5. Consult a local lawyer and take steps.

better to send a legal notice through lawyer after consulting him/her (offline/online) thoroughly along with relevant documents,

A partition suit can be filed in the city civil court.

File partition suit than settlement through LOK adalat or file pre litigation suit, there you will get mediator. NO arbitrator.

by mutual consent of parties arbitrator can be appointed to resolve the disputes 

See appointing arbitrator or.mediator won't yield result if other party doesnot agree.as it is not binding.

1. Arbitrator is appointed by the Court in case there is a provision for such appointment in an agreement which is the basis for a  dispute.

2. In your case, you shall have to file a partition suit claiming your share of the property as suggested in my earlier post.

file partition suit in jurisdictional civil court.

It's better you settle mutually.  Otherwise you need to file partition suit in civil Court

If one of the cosharers is creating problem and is reluctant to partition both the movable and immovable  properties, then the option before you is to file a partition suit and drag them all to the court of law seeking yor legitimate share in the properties as per your entitlement.

Let them answer the court when the case is going on.

You may take the advice of a local advocate and proceed with the sid partition suit.

Arbitrator may not be able to solve the issue since it is a personal issue, you can appoint  a mediator, but the mediator's  solution may not be acceptable to them hence you may have to revert to the court, instead you may directly approach court for a proper and legal solution to this.

Dear Client 

You should Go for mediation regarding this dispute as it is not a big issue and every one wants to give your share but the main issue is about how much the share would be.

Then My suggestion is that you should go for mediation which will be between you and person who is creating issue.