Apple ID & iCloud: How does one change "Alternate Apple ID"?

[anon(153966)]

I've searched for this a little, and now I'm even more confused than when I started.
When one logs into My Apple ID, here https://appleid.apple.com/ there is a field, "Alternate Apple ID".

Can that field be changed, anywhere? The reports online seem to say no, albeit, some seem to say otherwise, but the said steps don't work.

Thanks in advance
Ivan

PS: MODs, feel free to move this to the appropriate section. I was confused with which section to place it, since it relates to Apple ID & sort of iCloud...