Order Only: Private message to Draco Malfoy and Hermione Granger

I heard Mr Derrick joined the Order. My father's old clerk, Maghnus Derrick. Is it true? I also heard he can't come to Moddey and I don't know why, I want to see him. Can you take me to visit him some other place? Like Sirius Black's house where the meeting was everyone went to?