underage magic

[hpdmieboq]

No: HPFGUIDX 133960

OK, so I don't know if anybody has brought this up yet because i feel
like I'm drowning in posts but I had a question.

   I was rereading the book and realized that DD did a lot of magic at
Harry's house and according to what DD says about underage magic
later, Harry should be blamed for it.  Of course, DD isn't that stupid
and would have foreseen this and taken measures to ensure that he
could do magic at the Dursleys without Harry being blamed for it.  my
question is how?
   If he informed the Ministry about going to get Harry that seems too
risky in terms of someone could find out that Harry would be traveling
and, that seems like somehting that needs to be kept under wraps. 
Also, that would mean bringing more attention to the Dursley house. 
The only way I can see of DD getting around all this is if he had some
device/ spell/charm to either take the Ministry survelliance off the
house or mask his own magic.  I am very curious as to how he did this.
 He himself said that the Ministry has no way of knowing who does the
magic just that it was done, so I don't believe that they have some
way of recognizing that it was DD performing spells.  Whatever he used
could prove useful in the future, no?

I also found it odd that Harry wouldn't also come up with this
question, but maybe it will be answered in book 7?  Anyway, i'm
looking forward to seeing what kind of answers there are to this.

-Irka
(Who mostly just lurks but when she gets a question that bugs the hell
outta her she has to choice but to ask it)