Will lost/not produced

Though a family agreement has not been defined statutorily under Indian laws,  it as ‘an agreement among members of the same family, intended to be generally and reasonably for the family's benefit, either by compromising doubtful or disputed rights or by preserving the family property or its peace and security by avoiding litigation or by saving its honour’. What it effectively means is that the members of a family arrive at an amicable understanding, written or verbal, regarding movable or immovable property to avoid any existing or future disputes.

You can ignore the word Will present in the family agreement because if there was a Will then it should have been enforced by the beneficiaries sooner the Will came into force. 

Whatever you may consult a local experienced lawyer and proceed on the suggestion and advise received

The query is too speculative. When was the family agreement executed?

Is any of the parties to the agreement disputing its authenticity based on legally sustainable reasons?

Family agreement prepared almost 5 years back. The only dispute is that the Will mentioned in the agreement has not been shared with legal heirs.

Please prepare and execute a registred partition deed. 

Do not mention about the Will in the partition deed. 

Do not also mention about the family arrangement. 

You may mention that the partition deed is being executed based on oral allotments made by your elders. 

You do not have a will or family settlement/ arrangement it is better to file a suit for partition and possession through a local prudent lawyer.

Oral partition, if  acted upon, is binding upon the family members. And such evidence, in the eventuality of any dispute,  is admissible in a Civil proceedings.

Sir family agreement is there in which will is mentioned but the copy of the will is missing 

If the will is missing, then try to get another family arrangement without mentioning the will. 

Better than that is to draft a partition deed and register it. 

If the parties do not cooperate, immediately file a partition suit giving all the details. In the partition suit, you write that there was a family arrangement, will was mentioned in it, but the will is missing now. Let the other parties respond with their written statements. Let the Court hear all parties and pass judgment and decree. Preliminary and final decrees. 

After you file a partition suit, it is very likely that the parties will come for a compromise, if they need a quick settlement. You can reach a compromise agreement and  file a compromise petition in the Court and close the matter quickly. In the compromise agreement and compromise petition, you mention that there was a family arrngement, and will was mentioned in it, but the will is missing now. 

What else can you think of other than the above?

If the properties are situated in Bombay, Calcutta or Madras, or if the will is made in these three cities, then probate of Will is compulsory. 

Without probate of Will, the will not be legal in the above three cities. 

So, where are the properties situated and where was the will made? 

Even if you have the will, it will not be valid, unless probate is done. This rule is applicable only for Bombay, Madras and Calcutta. 

Probate of Will is not mandatory in other places of India. 

Therefore, the family arrangement will anyway be not valid, even if you have the will, if the probate of Will is not done. For Bombay, Madras and Calcutta only. 

Therefore, as suggested by other advocates here, the best option is to draft a fresh family arrangement or a fresh partition deed or file a partition suit. 

Try to do something fresh now.