Artemisia Auctions, which is handling the sale, expects the manuscripts to fetch up to 120,000 euros (USD 162,000) when they are auctioned off on November 6 at the Drouot auction house.
The codicils, or amendments, were penned in 1821 by Napoleon's field assistant, the Count of Montholon, when the former French emperor was in exile on the British island of Saint Helena.
"I want my ashes to rest on the banks of the Seine among the French people I loved so much," says one of the amendments, written on April 16, 1821.
In another amendment, he lists his possessions in Saint Helena, including furniture, jewellery, silverware, porcelain, weapons and books to be divided among his closest aides and his "good and dear mother."
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Napoleon personally wrote his own last testament, which is on display in the National Archives in Paris, but he had several copies made in case the British destroyed the original.
The codicils were in the possession of the Montholon family, who have now decided to put them up for sale.
Pierre-Jean Chalencon, the head of the Cercle France Napoleon group which aims to preserve the memory of the famous French leader, told AFP that Montholon had "used the same paper, the same ink and the same quill as Napoleon."