Questions about causative constructions


If I wanted to say "The teacher who made the kids write a letter to their
friend in the hospital", how should I write it?

Are 2 にs ok in the same sentence?  
Would 病院にいる友達に子供に手紙を書かせた先生。be acceptable?

If there are no particles, how should I interpret a causative like 書かせた人

Would it be

  1. The person who made someone else write
  2. The person who was made to write by someone




This sentence would be at least understandable if you change the word order
and write like this:

> 子供に病院にいる友達に手紙を書かせた先生

It's because this sentence will be parsed like this (with "nesting"):

> [子供に[病院にいる友達に手紙を書か]せた]先生

The "病院にいる友達に手紙を書く" part should be written as one verbal phrase because that's
the action the child has to take.

This question is more or less similar: [Multiple "wo"s in a
sentence?](https://japanese.stackexchange.com/q/23261/5010)

* * *

That said, it would be much better if you can avoid multiple に's like this.
Multiple に both marking a person is hard for even native speakers to
understand. The simplest way to fix this is using へ instead.

>   * 子供に病院にいる友達 **へ** 手紙を書かせた先生
>   * 子供に病院にいる友達 **への** 手紙を書かせた先生
>   * 病院にいる友達 **への** 手紙を子供に書かせた先生  
>  (This is okay, as @優しいエイリアン suggested, because への modifies 手紙, and
> 病院にいる友達への手紙 is one noun phrase)
>   * [*] 病院にいる友達へ手紙を子供に書かせた先生 ( **wrong** )  
>  (Can you see why this is wrong? へ modifies the verb 書く. The "nest"
> structure will be broken if you write like this)
>

* * *

And I see nothing wrong with sentences like this:

>   * 子供に夜にお菓子を食べさせるのは良くない。
>   * 夜に子供にお菓子を食べさせるのは良くない。
>   * 夜にお菓子を子供に食べさせるのは良くない。  
>  (uncommon word order, but perfectly makes sense)
>




This sentence would be at least understandable if you change the word order
and write like this:

> 子供に病院にいる友達に手紙を書かせた先生

It's because this sentence will be parsed like this (with "nesting"):

> [子供に[病院にいる友達に手紙を書か]せた]先生

The "病院にいる友達に手紙を書く" part should be written as one verbal phrase because that's
the action the child has to take.

This question is more or less similar: [Multiple "wo"s in a
sentence?](https://japanese.stackexchange.com/q/23261/5010)

* * *

That said, it would be much better if you can avoid multiple に's like this.
Multiple に both marking a person is hard for even native speakers to
understand. The simplest way to fix this is using へ instead.

>   * 子供に病院にいる友達 **へ** 手紙を書かせた先生
>   * 子供に病院にいる友達 **への** 手紙を書かせた先生
>   * 病院にいる友達 **への** 手紙を子供に書かせた先生  
>  (This is okay, as @優しいエイリアン suggested, because への modifies 手紙, and
> 病院にいる友達への手紙 is one noun phrase)
>   * [*] 病院にいる友達へ手紙を子供に書かせた先生 ( **wrong** )  
>  (Can you see why this is wrong? へ modifies the verb 書く. The "nest"
> structure will be broken if you write like this)
>

* * *

And I see nothing wrong with sentences like this:

>   * 子供に夜にお菓子を食べさせるのは良くない。
>   * 夜に子供にお菓子を食べさせるのは良くない。
>   * 夜にお菓子を子供に食べさせるのは良くない。  
>  (uncommon word order, but perfectly makes sense)
>

