The usage of '[sic]' is well defined for quoting a passage that you believe has an error in it: nearest to the mistake you place '[sic]' within the quotes. For example, suppose I write a letter from I to you. This last sentence of mine is counter to most norms of English writing (it's wrong), so in quoting it someone would naturally want to write:
...suppose I write a letter from I [sic] to you.
Suppose though that I do something else, suppose I write a letter from me to you. This follows accepted grammatical practice (it's correct grammar). But then further suppose that someone thinks you should use 'I' instead of 'me'. And they quote it thus:
...suppose I write a letter from me [sic] to you.
The '[sic]' has been mistakenly used.
But how do you quote the passage I just wrote? Would it be:
"...suppose I write a letter from me [sic] to you." [sic]
"...suppose I write a letter from me [sic] [sic] to you."
"...suppose I write a letter from me [sic [sic]] to you."
None of these sound right to me: the first because it doesn't point out where the error is, the second because you can't tell (for either '[sic]') if you're using '[sic]' or it is part of the thing quoted, and for the third example...well, that might be a way to mark the error, but surely the mechanics of '[sic]' could have been designed better to begin with.
So which of these three, or something else entirely, should be used for quoting a passage where '[sic]' is used wrongly?