If we say 'whose' In Dutch, we have to make a distinction between feminine and masculine owners. If we refer to property of a masculine owner we say _wiens_, if the owner is feminine or if there are several owners (plural): _wier_.
Is dat de man wiens vrouw vanavond op televisie was? | Is that the man whose wife was on television tonight?
De jongen, wiens zusje bij jou in de klas zit,... | The boy, whose little sister is on your class,...
De actrice, wier faam in de jaren veertig begon,... | The actress, whose fame started of in the forties,..
De meisjes, wier ouders uit Marokko komen,... | The girls, whose parents come from Morocco,...
While _wiens_ is still very common, _wier_ is considered rather formal. People often use _wiens_ even if the owner is feminine or plural. Personally, I would rather opt for the alternative below.
_Van wie de_ / _van wie het_
Instead of 'whose', you can also say 'of whom': _van wie de_ or _van wie het_:
Is dat de man van wie de vrouw vanavond op televisie was? | Is that the man whose wife was on television tonight?
De jongen van wie het zusje bij jou in de klas zit,... | The boy, whose little sister is on your class,...
De actrice, van wie de faam in de jaren veertig begon,.. | The actress, whose fame started off in the forties,..
De meisjes, van wie de ouders uit Marokko komen,... | The girls, whose parents come from Morocco,...
Whether we use _van wie de_ or _van wie het_ depends, of course, on the noun it precedes ( [de or het](#/lesson/NounsAndArticles.03)).