I have good news and bad news on this front.
The good news: at least as far as APRC is concerned, changing nationality is officially supported as of last year.
The bad news: the document requirements are nonsense and I don’t know what would satisfy them.
I could not get a straight answer out of them what “sufficient evidence” is. Just some sort of document that says citizen of country A is also citizen of country B. It’s literally immigration’s job to decide if someone is the legitimate holder of a passport or not. 