Singapore name translation

Chinese in Southeast Asia, including Chinese in Singapore, can only write English Pinyin when registering their identity cards, but most of the early Chinese were illiterate, so when applying for identity cards, they all read their names to foreign officials in their own voices, so the names are spelled according to the pronunciation of their native places.

I suggest you don't have to go to so much trouble. If you are not from there, write your name in Chinese Pinyin. So my suggestion is to write "Yan" as "Yan".

Unless you want to lie to Singaporeans that you are a local, I'm sorry, this surname is rare in Singapore, and it will be revealed as soon as it is displayed, hehe.