So I'm in the same boat/plane as you right now. I'm on a non-refundable fare. Don't want my child to be exposed overseas, so I've done a bit of calling all of today with both Chase and SQ.

What a fricken waste of time. Chase doesn't really know left from right. SQ refuses to talk to me about anything.

What I could gather from all of this is:
1) If your area is covered by a waiver of change fees, you may change at no additional cost but obviously pay the fare difference.
2) If you wish to cancel, there is no fee to do so, and they will supposedly credit the entire fare amount to you, but when you want to rebook with those credits, it will cost you $200/pp out of that credit to rebook.
3) The credit is valid for a year from your original booking.
4) Chase said you can use the credits to book from your origin country to any destination flown by SQ, so we are looking for other destinations now that kind of match our original fare but has little exposure.
5) If you no show, you technically forfeit the amount, but can ask to claim the fare in credits, +rebook, +maybe an additional no show fee (supposedly $200).