Arguments vs. adjuncts as heads of relative clauses

[Waruno Mahdi]

Sorry this isn't really an answer to the query, because I'm not
aware of knowing a languge that doesn't allow construction (3) -
- indirect object as head of relative clause.

But in Indonesian, constructions (5)-(6) are achieved by an interesting
"trick" which can however be avoided in (5) when one rephrases it with a
passive voice form of the verb in the relative clause - (5a)

(1/4) The woman [who is singing a lullaby] is holding a baby.
      Wanita [yang sedang menyanyikan lagu ninabobo] itu sedang menggendong
bayi
     (woman [REL DURAT singCAUS-ACT song lullaby] DET DURAT carryACT baby)

(2) The woman is holding a baby [who is sleeping].
    Wanita itu sedang menggendong bayi [yang sedang tidur]
   (woman DET DURAT carryACT baby [REL DURAT sleep])

(3) The baby is held by the woman [who is singing a lullaby].
    Bayi itu sedang digendong oleh wanita [yang menyanyikan lagu ninabobo]
   (baby DET DURAT carryPASS by woman [DET singCAUS-ACT song lullaby])

(5a) The baby [that is being held by the woman] is sleeping.
     Bayi [yang sedang digendong oleh wanita itu] sedang tidur
    (baby [REL DURAT carryPASS by woman DET] DURAT sleep)

(5) The baby [that the woman is holding] is sleeping.
    Bayi [yang wanita itu sedang menggendong-nya] itu sedang tidur
   (baby [REL woman DET DURAT carryACT 3psOBL] DET DURAT sleep)

(6) The woman [that the baby is being held by] is singing.
    Wanita [yang bayi itu sedang digendong oleh-nya] itu sedang nyanyi
   (woman [REL baby DET DURAT carryPASS by 3psOBL] DET DURAT singSTAT

In (5) and (6), the role to be attributed to the head of the relative
clause is duplicated within that clause by -nya (oblique-case form of
the third person singular pronoun _ia_).

Salam,  Waruno