Is it grammatical to say
I have a friend whose father I respect so much
when there are the following facts:
- I have a friend
- I respect his/her father so much
For the use of "whose", your sentence is grammatical. "Whose" is an adjective and is not either subjective or objective. It is the noun ("father") that is the object, not "whose". "Whose" is simply giving more information about "father". Your use of "so much", while common, is not ideal. It would be better to use "very much". As it stands, you respect him so much as what? You might say something like "There are few people I respect so much as Johnny's father." There you are comparing other people with Johnny's father. It would also be fairly common to use "as much as" or "more than" in that case.