Documents required to Tourist Visa of Unemployed mother

[Prisha]

Hello,

I am planning to invite my mother to visit us from India. Me and my husband we are going to sponser all her trip cost. My mother is unmployed and financially depend on my father. My father is still working. So my questions are :-

1. How much minimum saving is required to be shown from my mother's side?
2. What are the dcuments required to show her source of income is basically my father's income. (Here can we attached my father's employment letter, bank statements of salary account and pay slips?)
3. Documents required to show her ties to home country?
4.Is any addtional cover letter required signed by my mother stating her financial dependacy on my father?
and also she is willing to return to home country after her stay in UK as she has family there to look after.

Also on her passort they have mntioned that "Imigration check required" as we failed to provide the NON-ECR category documents while doing passport. Will that affect her uk tourist visa?

Please help me with all these doubts.

Thanks in advance.

[Prisha]

please reply with expert advice.