I know the relative adverb "where" can be used in a non-defining relative clause like this.
"I've just come back from London, where John lives."
Can I use "in which" instead of "where" in this sentence?
"I've just come back from London, in which John lives."
Is the latter grammatically correct and functionally equivalent with no difference in meaning?
Is there any grammar rule that we can't use commas in front of "in which"?