The UK immigration system is (and has been, for the past ten years) hostile towards chain immigration (one member of the family pulling the rest of the family over) and generally tends to limit immigration to just the spouse and children of the original migrant.
Visit visas have an expectation that the applicant would return back to their country of habitual residence within six months and generally proof of strong ties to their home country are required at the time of application submission. Having their only child living in the UK considerably
weakens their case as it is not clear what incentive there would be for the applicant to leave the UK, while there is a strong reason for them to overstay.
In order to apply for a five or 10 year visa, you need to start by applying for a six month visa and then, once that is granted, create a history of their meeting the terms of their visa by returning to their country of habitual residence before the end of their visa. Then, after a few six month visas, they can move to a two year visa and then progress to a five year or ten year visa. It is not dissimilar to building up a credit history with banks and credit cards.
Also keep in mind that the UK's interpretation of a visit is much shorter (measured in a few weeks) than the typical Indian interpretation (measured in months) of a visit.
If Covid were a valid reason, half the Indian population with family in the UK would be living here. I am not entirely sure that that will be acceptable as a reason.
As an aside, if applying for a visit visa, be sure to get a good health insurance plan for them, as visitors are not covered by the NHS and are charged 150% cost if NHS services are used during the visit.
In any case, be aware that
Adult Dependent Relative (ADR) settlement visas are extremely difficult to get, with only 6% chances of approval and a further 16% after appeals. So, even after appeals, the failure rate is about 80%.
The requirements are quite high. You need to prove that the applicant (your parents) need assistance with basic personal needs (bathing, washing up, etc) AND that such care is either unavailable or unaffordable in their country of habitual residence. Given that the cost of living and hiring help is relatively low in South Asia and so the second requirement generally fails, most applications from that region of the world tend to fail.
There is also an underlying expectation that one parent can take care of the other. Most successful ADR applications on these forums have (a) involved single parents and (b) been from the US and similar countries (where the cost of hiring care is much higher).
Both the visit visa applications and the ADR applications would seem to me, to be uphill battles in your case, with the latter being more of a Mt Everest than a mere hill.
If you are very deeply concerned about the care of your parents, you may want to start planning on moving back to India and taking care of them there after you acquire British citizenship. Keep in mind that if you choose to go down that route, there may be consequences for any children who will be born to you abroad, who will themselves be British citizens, but who will not be able to pass their British citizenship on to their children (your grandchildren).
I am not a lawyer or immigration advisor. My statements/comments do not constitute legal advice. E&OE. Please do not PM me for advice.
