Undeciphered letters from Duke of Guise? (ca.1581)

Here are undeciphered letters to Mr de Mercoeur probably from the Duke of Guise.
I have been planning to write a background article but it will still take time. In the meantime, see
"Catalogue of Ciphers (Mainly Related to Duke of Nevers) in BnF fr.3995" for some contemporary French ciphers.
If someone achieves deciphering these, please let me know.