The last time I had a similar situation a DFW to LAX/LAX to LIH flight delayed multiple times but finally cancelled well after dark. Perhaps because it was so late on a bad weather day AA sent out three of the most together GA's ever to the gate, rather than sending everyone to a rebooking line.

The default was being rebooked onto a similar connection the next day, but if you had another idea they were all ears. We asked for DFW to HNL/HNL to LIH on Hawaiian, which would get us to our somewhat remote hotel well before dark rather than after.

It was entered as an online ticket request. But, she did comment first that "She could not force Hawaiian to pick up the booking". But apparently they did. She handed us the new boarding passes. Followed by a comment "they don't always accept the booking so quickly".

I'm not sure if that is relevant or not. But it did appear the alternative carrier could decline.