settlement visa

hi everyone!
Am British by birth so is my sister,we have a sister who is back in africa and not a British like us.our parent are both late.she is wholly dependant on us both financially and emotionally as we are her only family.
she has 3 children, one of which got burnt and died when her house caught fire about 6years ago
now she lives in a slump and this too got burnt last year in this case she lost documents.however since d first fire incident she been emotionally drained and psychophysically too. she is on medication for anti depressant.the doctor that treats her has advised that she should not be left alone to look after the kids as she is not fit enough to do so.
Myself and my other sister have now decided to bring her to join us with her kids(whose fathers left her the moment she told them she is carrying a child)
we have not seen her in over 10years
can anyone help as what our best options is in this case.

So she's going through all this hell and you haven't bothered to see her in 10 years? I have sisters and I can't imagine not even visiting once for that long.

Yea!but what I need now is advise on how to bring her to join us. Thanks

Can you explain why you and one sister are British, but your other sister is not. How has that happened?

Also, in which country does the other sister live? and how old is she?

At the time of our birth, our parents both lived here in the UK.They had both returned back to their country of origin by the time our sister was conceived and subsequently born.she is 33years and in nigeria

Did either of your parents get British Citizenship? If yes, your sister in Nigeria is also British, even though she was born in that country.

But if no, I do not think your British status helps your sister in any way, unfortunately.

they didnt get citizenship before going back. but i was thinking about the part that says 'other relative comeing to join a person settled in uk'

Dependent relative visas are very difficult to obtain, and also very expensive to apply for, and I doubt whether your family members meet the criteria.

But other opinions very welcome.