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).
Questions? 
