Not sure what is the perfect working for this scenario - Money, Changing someone's mind

[Big Dipper]

I was supposed to come into an amount of money that would've helped me significantly in terms of retirement and in terms of donating to the Jos, so here's the context:
Someone I know happens to own half of a farm
Their sibling wanted to buy out this person's half for 500,000 dollars
I was going to get a fraction of that as a part of this person's inheritance
This person wanted to have the farm Reevaluated to get the true cost of the farm
That angered the sibling into retracting the offer, so now the half of the farm is not being bought out and I'm not currently getting the inheritance

Here's my question: What magical working would be best for me to do to get this person to change their mind, or should I do something money related? Seems to me the root of the problem is the sibling's greediness ( I'm not 100% sure why they got mad when a Reevaluation got mentioned, but I assume it's because their half of the family is bigger and wants to have more to give after death rather than a 50/50 as the farm is probably worth more than 1 million)
I planed on Donating a fraction of what was planned on being given to me and using the rest to build up my retirement. I just don't know how to approach this issue, be it a money working, a working to change a mind, or me simply bringing up to them to just accept the 500k they were offered even though it's probably not fair to them. Thank you.

When I get this money, and if I get to keep the actual amount offered to me without getting kiked by taxes, Lord Satan and the Gods of Hell have my word I will give the promised amount I'd come up with and in addition a certain number every month whenever my retirement checks were to start coming in (which I have no idea what that would be yet, I plan on getting a Universal Index Life insurance policy)

 

[logicalmind]

Is it really necessary in your scenario for that sibling to buy that half, so you would get your desired fraction? What if someone else would offer more money for that half to be bought? Wouldn't this situation be better for you?

 

[Big Dipper]

Is it really necessary in your scenario for that sibling to buy that half, so you would get your desired fraction? What if someone else would offer more money for that half to be bought? Wouldn't this situation be better for you?

I don't think anyone else would buy it, plus they might prefer to keep it in the family.