Adult daughter form India to join elderly mum in UK

[biggurs]

Hi all
This is my first post.
My dad came over to the UK in late 60's.
My mum joined him in 1970. Dad was UK citizen. Mum remained Indian Citizen but has indefinite leave to remain.
Dad passed away 10 yrs ago.
I have a sister that remained in India, she had just got married when mum came to the UK.
My sisters husband passed away about 9 yrs ago.
My mum is now very old and ill.
My wife is her carer.
Can I call my sister from India to live in the UK because she has no family in India. (apart from grown up children who are mainly now married except for 2 who are over 16 but not married)
They both NEED to see each other for last time but my mum cant travel.
I know she can come for a visit (I was born here in the UK and have a good profession etc so I presume i can sponser her) but is there any legislation or law that enables someone like my sister to emigrate here to the UK as all her family is here, she is widowed and in her 50's now.
Any help will be very much appreciated before I arrange to see an immigration solicitor but I really need to know where I stand.
Thanks everyone

[Lucapooka]

She can't settle in the UK. For an adult relative to qualify for settlement they need to be living in extremely compassionate circumstances such as indigence and illness with no local support.

[biggurs]

Thankyou lucapooka
Where is my first port of call to apply for her to come to visit our sick mother?
Thanks

[Greenie]

If you want her to visit she can apply for a family visit visa.

[geriatrix]

How to apply for a visa?

[biggurs]

Thankyou for that.
On the form it asks specific dates of travel.
How will one know what dates they will travel unless they have confirmed airline bookings, but who will book a flight to the UK only to find out a visa was refused?
Thanks in advance

[geriatrix]

The form asks for the "date you wish to travel" and not "date you will travel"!
Wish can change.

[biggurs]

Oh sorry I didn't realise.
Thanks again for all your help.