UK visitor visa - advise needed

Dear All,
I'm planning to apply visitor visa for my in laws bot father in law and mother in law. I'll be sponsoring their entire trip. I'm clear on documents I need to provide. My question is related to the documents to be submitted by my in laws. They don't have any property in their name. Father in law is a retired government official and mother in law is a home maker. They can produce
1. Bank statements of my father in law. Sufficient funds are there
2. Proof of monthly pension amount into the same bank account.
3. Retirement certificate as a government employee
4. Passports and other address proof

My worry is since they don't have any property. How to I prove they will return to India at the end of their visit? Will the above proof sufficient?

They have a son who is in India. He is not married and working. Can I give proof that he is their son, working which proves their social need to go back to India?

Please advise me.

Thanks

Hi I believe that is a good start, maybe provide a family tree or family photos as well of extended family.

Are they active members of any groups? i.e my father in law was the secretary at the local temple, and he got a letter from them.

Most Visit Visa rejections have been on lack of ties to home country, so make sure you cover it off best you can.