Essentially try and keep the British Raj as a system of colonial government alive without moving to democratisation and dominion status. Alternate solutions can be used as well so the government structure doesn't need to remain static. Also, the Raj doesn't necessarily need to obey parliament and could eventually unilaterally declare independence if that works as well. The earliest allowed POD is 1890AD.
Avoiding both World Wars is necasary in both scenario’s, with both wars making retaining control of India practically impossible.
However as the decades go by retaining control will remain increasingly hard.
I can’t see control being maintained past the 1970’s at the latest and that would probably consist of a bloody rebellion.
It’s a system that can only be maintained as long as the British Empire remains strong, something that is impossible to maintain.