If the property is originally owned by 5 sisters. And the 3 sisters sold there share to 1 sister for $10,000 each except for 1 other sister...

Question

If the property is originally owned by 5 sisters.

And the 3 sisters sold there share to 1 sister for

$10,000 each except for 1 other sister did not sell.

The new owner sister now sold over the property

To a buyer John doe. After the property was sold,

John doe is now being sued by the 1 sister that did

Not sign off her name and collected her $10,000 as

All agreed earlier. She wants now john Doe to pay

$30,000 instead, does she have a case?

What does John doe needs to do in court to fix this?

Answer

This looks like a search for help with homework. It is the policy of the board to not answer homework questions.

However, if the situation is a real life event, you should consult with an attorney who handles real estate matters. Your facts aren't completely coherent, but they appear to be more complicated than what can be adequately addressed in forum such as this.