I'm writing a story for an Indian movie that revolves around a bunch of estranged siblings, who come to live in their father's abandoned house a year after his death. They do so because they receive knowledge that there is a huge treasure hidden in that house. I want to understand the best way to structure the story. If there is a format that could be followed, it would be great.
There's no characteristic structure for treasure-hunt stories. For example, it wouldn't help you to read the quintessential example Treasure Island, because the fact about that novel that most impacts its structure is not the presence of a treasure hunt, but its being a coming of age story for Jim Hawkins.
The best stories, whether they involve treasure-hunting or otherwise, have fantastic character development. What will happen to your characters? Will they move past whatever estranged them despite the family connection? Or will initially minor disagreements eventually become something very dark out of competition for the treasure? That's up to you, and you might do a combination of these ideas or something else. But if you want to plan your story and its structure, you might find it best to work backwards from such decisions to the plot itself.
Let's say the siblings look around the house, find something confusing, realise its implications for how they could find the treasure, keep following the threads, eventually get it and decide how it should be shared and used. They'll learn a lot about the house, and probably family members, along the way; and the things they learn are far more important to character development than the $$$.
How was the treasure accrued; were the means honest, and were they what everyone thought going in? Is the treasure itself what people thought it was? Why was it hidden there, and why did no-one get it yet? Do all the siblings know, or think, the same things going in? If their knowledge differs, does it create conspiracy against others or the suspicion of it? How does the geography of the house help subsets of the group talk behind others' backs?
I'll leave it with you.