It's a new product that seems to have been quietly introduced last week. Allows you to buy a neighbouring seat or an entire row in economy three days before departure. https://www.malaysiaairlines.com/my/...t-unveils.html

I don't have any MH flights in Y coming up until Feb 2020, so if anyone has tried it, would love to hear how much MH is charging for this. The option is available under "My Trip" on the website; can't find it on the app.