@David, Moderator posted:
"For" is fine if we understand the "which"-clause to be modifying the noun phrase headed by "altercation." And that is how I understand Jacob's relative clause—not as a sentential relative clause, but as a normal nonrestrictive relative clause.
- The father got into a physical altercation with the mother.
- The child was present for it.
- The father got into a physical altercation with the mother, which the child was present for.
The manipulations you have used, Jacob, in the various options tell me that you think a relative clause needs to follow "altercation" immediately if it is to modify that noun. That is not the case. The relative clause is one of many modifiers.
That sentence does not really work. Sentential relatives do not work when "which" functions as the object of a preposition. We can add a noun, such as "occasion," after the preposition, but that changes the structure.
When a prepositional phrase occurs as an adverbial modifier in a clause, even as part of a phrasal verb construction ("put up with something"), the complement (or object) of the preposition will be a noun phrase, not a clause.
Thus, the reader/hearer will understand (or try to understand) the antecedent of a "which" that functions, within its clause, as the object of a preposition as referring to a noun phrase, not to a clause.
But for a sentential relative clause to work as a sentential relative clause, the "which" must be understandable as referring to the propositional content of a clause which it is modifying. Try to use verbs that can be followed by "that":
- The father punched the mother, which was too much for the child to bear.
(= The father's punching the mother was too much for the child to bear.)
- The father got into a physical altercation with the mother, which was too much for the child to bear.
(= The father's getting into a physical altercation with the mother was too much for the child to bear.)
I hope I'm understanding what you've said above. I'd like to give a few examples to see if I've got this.
I believe this is a normal nonrestrictive relative clause modifying a noun phrase:
(A) The current order states that the parties must follow the agreement signed on 3/24/21, which states that the parties shall share custody.
I believe this is a sentential relative clause modifying a verb phrase:
(B) The father punched the mother in the face, which resulted in the mother sustaining bruising.