Mother in law can execute registered relinquishment deed to relinquish her share in property 

you can apply for mutation of property in name of other legal heirs 

legal heir certificate may not necessary unless insisted upon by authorities 

Widow is class one legal heir of deceased husband with daughters. Basing of marriage certificate she entitled to be included in legal certificate. Nationality will not affect her right as widow. Legal heir certificate is issued  by Tahasildar in Tamil Nadu, application  for such certificate can also be submitted online on Tamil Nadu State Government  website and physical verification offline by revenue officials. This is the link.

https://services.india.gov.in/service/detail/apply-for-legal-heirship-certificate-in-tamil-nadu-

- As per law, after the demise of your father in law , his property would be devolved upon his wife , and two daughters equally i.e. everybody will get 1/3rd share in the property. 

- Further, even his wife is a foreigner , she is entitled to get share in the property of husband 

- However, she can execute a relinquishment deed in favor of her daughters for releasing her share. 

- Legal heir certificate may not a requirement for getting share in the property 

- Further, your wife and her sister can apply for mutation for naming the property in their respective name. 

Dear Client,

A Non-Resident Indian or a Foreign national such as UK, US or Canadian citizens can inherit the property in India from anyone including their relatives. So it is advisable to include your mother-in-law as the legal heir.

Hope this clarifies your query and requirement.

Thank you.

Your mother in law whether an Indian or foreign citizen, is still a legal heir/successor in interest to succeed to the estates left by her husband who is reported to have died intestate, hence you may have to obtain a legal heirship certificate by including her name too.

The marriage certificate to prove her marriage with her husband would be sufficient to prove her relationship with her deceased husband.

Yes you can get the legal heir certificate for all heirs of the said property if property is from India

• As per the Hindu succession act 1956, the first class legal heirs will obtain the properties by way of inheritance from the person who deceased intestate. The first class legal heir to the Hindu Who died intestate are his 1. Mother 2 . Wife. 3 sons and daughters. Therefore, in your case, your father in law ‘s legal heirs are his wife and daughters. If her mother is still alive then she will also get share on her son’s property. Being a foreigner that will not preclude your mother-in-law from getting her husband’s  property. Therefore, her name should be mentioned in the  legal heirship certificate. Thereafter she can execute a settlement deed in favour of her daughters by relinquishing her right in the properties if she wishes . Hope, I have cleared your doubts.

Your mother in law is also a legal heir. Check online for application.

After the intestate death of your father-in-law, his estate devolved equally upon all his legal heirs, your mother-in-law, your sister-in-law and your wife, by automatic succession. Your mother-in-law cannot be excluded as a legal heir. She has to execute and register a deed of relinquishment surrendering her one-third undivided share in your father-in-law's estate in favour of her two daughters.