Regarding adjoing property

My mother-in-law and her sister inherited an adjoing property as sthridhana from thier grandmother in 1989. The last will was made by theri grandmother in 1989. The contents of the will are:1.Both of them had no powers of alienation or transferring the property 2. they shall enjoy the property during their lifetime and after their lifetime the property goes to their respective daughters. My mother-in-law has a son and a daughter and her sister has four daughters. 3.My mother-in-law passed away in November 2015 and her sister is very much alive.When my mother-in-law was alive , a family arrangement was made between my husband and my sist. As per the will my sister-in-law gets the title of the property. we have one more property . By mutual consent , a family arrangent was made between my husband and my sister-in-law and the sthridhana property was exchanged with the other property and the family arrangement was registered in sub registrar office. According to the family arrangement , my husband got the title of the property after my mother in laws death.Now my mother in laws sisters four daughters want to sell their property. But my mother in laws sister is very much alive. Further we have a common passage according to the will made in 1989 and it is about 615 square feet. According to the will, there is no need on NOC to be given by my husband. But my mother in laws sisters daughters are requesting for a NOC , as it was demanded by the prospective purchaser to use the common passage by him. There has been an encroachment of 5ft in our property. My question is: 1. Shd my husband give an NOC? 2. What are the repurcussions if my husband gives the NOC? and if he doesnt give? 3. According to the will the property cannot be sold , as my mother in laws sister is very much alive.So , Is it right on their part to sell the property and violate the conditions in the will? 4.We want to demarcate our property limits.. Our property is in the front portion and their property is in the backyard. According to the conditions in the will, there must be a 5ft space between the two properties and the aforesaid 5ft is the common space , where they have constructed a staircase which leads to their first and second floor. Ther is also a condition regarding the common passage in the will. That is no construcion or erection or any other structure can be built on the common passage by any of the two parties,, as the sewerage lines, water lines a and the electric lines run below the common passage. Now , Can my husband take a legal action on them for the same and can he challenge the will as the conditions in the will are violated? Especially No alienation powers during the life time of the two parties. can my mother in laws sister sell the property ? can my husband file a suit for the same?