More advanced grammar problems
When, where and how do/should I use "in which, of which, from which, to which and how?" I do not what to substitute that in place of any of the previously written statements. THANK YOU!!!
1 Answer
Which is used as a relative pronoun, as long as it's not human and it's used in a non-restrictive clause, ie it adds a bit of non-essential information that if left out would still leave a complete sentence: (making it different from the word 'that') eg:
My favourite dress, which is red, might suit you too.
but your other examples 'in' which, 'of' which and 'from' which are just a combination of a preposition and a relative pronoun.
The 'in', 'to' and 'from' combinations can be used to introduce a relative clause after a noun which (je je) refers to a place.
There's the hospital in which my friend had their operation.
There's the house from which the smoke was billowing.
Sometimes though it is just easier to the word 'where':
There's the hospital where my friend had their operation.
You can also use these combinations to begin questions:
In which hospital did your friend have their operation?
From which college did you graduate?
etc 
