NHI for Foreign Spouse of Foreigner

I have had a look through the posts here, and at the website (English and Chinese).

As far as I can tell my wife, who is here on a visitor visa, is eligible for NHI, and there is no requirement that foreigners must have a resident visa in order to apply. It does say that those with ARCs through work (my situation) must enroll, and I have, via my employer, but it does not say only those with resident visas are eligible. It simply lists “spouse” as an eligible dependent.

Will the NHI for my wife have to be processed through my employer ? Will they refuse because she does not have a resident visa ?

Does anyone have any references to laws or regulations on the matter ?