@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.
Am I right in thinking that the comma before "which" would be optional?