Donald inherited a number of legal issues when he bought the club from Ellis Short last year, but managed to banish a large number of cases filed against the club.
Only one remedy by Alvarez has been filed against the club, bringing Sunderland to the Sports Arbitration Court for loss of earnings.
And Alvarez's claim refers to the time when the two clubs were arguing about his future and he felt he had lost wages.
While agreeing on an agreement, Donald has revealed that Alvarez is now trying to secure a higher sum.
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He tweeted: "Yes, the court has ruled and we had to make a payment, but the player has objected to the amount and is seeking a higher agreement.
"So we're waiting to find out if the amount is going up."
But once the Alvarez case is fully resolved, Donald has confirmed that the "negative" cases faced by the club will be over.
"No against us," he posted.
"We have a few commercial ones in our favor, but this is the last negative."