If I use Renly´s Courtier to blank a Char with No Attachments and then Atach it a Milk of Poppy, what happens at the end of the phase?

I think Milk doesn´t discard, but just to be sure.

thanks

As his text box is blanked, the Milk should not be discarded because "No attachments" does not exist anymore.

Correct. Since both the Courtier and Milk of the Poppy are making the text box blank, it's not like the "No Attachments" comes back if only one of the effects wears off.