Nymphadora Tonks = Weasley cousin?

[hickengruendler]

No: HPFGUIDX 75626

First of all, this is of course pure speculation. But I remember, 
that JKR said in an interview, that there was supposed to be a 
Weasley cousin in book 4, that should have played a similar role as 
Rita played later. But because of a plothole the cousin vanished, but 
JKR said that she might include her in later books.

Now my question: Is it possible, that Tonks is this Weasley cousin? I 
mainly ask because
1: I don't see her purpose in book 5. She was quite nice, but really 
the most unimportant of all the new characters, who played sort of a 
mayor role. She is sort of an unimportant and in the end even 
underdeveloped character, yet, in contrast to most of the other new 
order members, at least she had sort of a character.

2: Her ability, being a metamorphagus, is ideal to spy on people. She 
could have disguised herself as another person each time to listen to 
Harry's, Hermione's and Ron's conversations, and therefore could have 
given informations to Rita, without being to suspicious. Of course 
this would have meant, that she was originally supposed to be a 
rather nasty character, and that it was maybe changed, because JKR 
wanted to bring her in somehow, and the Order seemed to be the best 
opportunity.

Maybe the plothole was, that Tonks, even as a Metamorphagus, wasn't 
able to spy when Harry had the vision in Trelawney's class (and this 
is a very important scene, because it is the beginning od the misitry 
etc. not believing Harry). So unless she had kidnapped Trelawney to 
disguise herself as Sybill (or one of the students), she wouldn't 
have been able to see Harry's breakdown. So it was changed and Rita 
became a beetle-animagus.

Hickengruendler