I was just told by a UA rep that standby no longer exists, just same-day changes. I was thinking this can't be true, so thought I would come here to ask. This can't be right??

Basically, I have a return IAH-ORD-HKG flight tomorrow that I want to push back later because I want to spend more time with my grandmother who has been extremely sick, and it is quite likely I will not see her alive again. (I didn't buy a bereavement fare -- just took off with the cheapest ticket I could fine asap.) Basically there is no fare released into the bucket I booked (L, amazingly) without paying over $1k for a SDC. Went to call an agent, and all the options I looked at are still amazingly expensive.

Honestly, any extra hours I can spend with my family would mean so much to me at this point. (I'm Gold, if that matters.)

My questions are:

1) Is it possible to standby for a later flight?
2) Is it possible to do an international standby on all United metal now?
2) IF ITS POSSIBLE, does this mean I have to go to the airport to be put on the list?