After the death of an elderly millionaire, his estranged offspring haul their families cross-country in order to retrieve their deceased father’s inheritance.

As Nir Shelter said.

And there ought to be stakes. They don't just want the money, they desperately need it (to stave off bankruptcy, pay for an expensive, life-saving operation, etc.). And soon.

Agreed with Peter.

It isn't clear if this is a comedy or drama so best to re draft the logline with that in mind. Also better to specify a main character and perhaps pin him or her up against their siblings in the journey. Otherwise it is hard to picture how the main action of the film will play out.

Hope this helps.

If you?re going for a family comedy kind of thing then I would write something like this:

When an elderly millionaire dies, his estranged(or *bickering*) children and their families are forced to take a road trip together across the country to retrieve their father?s inheritance.

It creates a sense of conflict/tension and show there?s potential for funny moments.

Hope this helps.