In German, demonstrative pronouns can be used in the genitive case to show possession or relationship. For plural nouns, you must choose between two similar forms: derer and deren.
The choice depends entirely on direction: whether you are pointing forward to new information, or pointing backward to a noun you just mentioned.
Pointing Forward with "derer"
Use derer when you want to say "of those" and are about to explain who those people are. It points forward to the rest of the sentence, and is almost always followed immediately by a relative clause.
| We would like to alleviate the poverty of those who have nothing. | Wir möchten die Armut derer lindern, die nichts haben. |
Notice how derer directly anticipates the relative clause (die nichts haben).
| The gratitude of those who live in the orphanage is great. | Die Dankbarkeit derer, die im Waisenhaus leben, ist groß. |
Pointing Backward with "deren"
Use deren when referring back to a plural noun that has already been established. In English, this often translates simply as "their."
| Since the foundations are generous, we admire their donors. | Da die Stiftungen großzügig sind, bewundern wir deren Spender. |
Here, deren points back to die Stiftungen. While you could use the standard possessive ihre ("their"), using deren is a slightly more formal way to say "the donors of those (foundations)." It is especially useful for avoiding ambiguity when a sentence contains multiple nouns that "ihre" could potentially refer to.
| We give orphanages and their children financial help. | Wir geben Waisenhäusern und deren Kindern finanzielle Hilfe. |
| Donors and their families work together in order to reduce poverty. | Spender und deren Familien arbeiten zusammen, um die Armut zu reduzieren. |