Learn Hardcore Indonesian: Sudahkah kamu sampaikan salam kepada orang tuanya? - Have you conveyed greetings to her/his parents?

-kah is a clitic that turns a clause into a yes/no question and lightly focuses the word it attaches to.
It attaches directly to the focused element: Sudahkah kamu…?, Maukah kamu…?, Apakah kamu…? (here -kah attaches to apa).
It sounds more formal/literary than everyday speech.

Is Sudahkah… natural in conversation? How else would people ask this?

It’s correct but formal/polite.
Casual alternatives:
- Udah kamu sampaikan salam ke orang tuanya?
- Kamu udah sampaikan salam ke orang tuanya belum?
- Udah titip salam ke orang tuanya?
- Udah bilang salam ke orang tuanya? (very casual)

Why is it sampaikan and not menyampaikan?

After aspect/modals like sudah, belum, bisa, mau, Indonesian often uses the bare verb (without meN-), especially in speech: sudah sampaikan, bisa kirim.
The fully affixed form is also fine and a bit more formal: Sudahkah kamu menyampaikan salam…?
Both are acceptable; just keep your register consistent.

What does the suffix -kan in sampaikan mean?

Base sampai = arrive/reach.
sampaikan ≈ cause something to reach someone → deliver/relay/convey.
It commonly allows a recipient, marked with kepada/ke: sampaikan [salam] kepada [orang tuanya].

Could I say titip salam instead of sampaikan salam? Any difference?

Sampaikan salam = deliver/relay greetings.
Titip salam = I entrust you to pass on my regards; slightly warmer and idiomatic.
Both are common: Tolong sampaikan/titip salam saya kepada orang tuanya.

Why kepada and not ke or untuk?

kepada is the careful/neutral preposition for recipients (especially people).
ke is very common in casual speech: … ke orang tuanya.
untuk means for (beneficiary/purpose), so it doesn’t fit this recipient meaning.

Who does -nya in orang tuanya refer to?

-nya is third person: his/her/their, or sometimes a definite marker (the).
Here it most naturally means his/her parents (someone mentioned in context).
If you mean your parents, say orang tuamu (informal) or orang tua Anda (formal).
In some service/casual contexts -nya can politely refer to you (e.g., KTP-nya), so context matters.

Can orang tua also mean “old person/people”? Is there any ambiguity here?

Yes, orang tua can mean parents or old person/people, depending on context.
In a greetings-to-recipients context, kepada orang tuanya will be understood as parents, not old people.

Is the word order kamu sampaikan normal?

How do you answer this kind of Sudahkah…? question naturally?

Use sudah (already) or belum (not yet), optionally with details:
- Sudah, tadi pagi.
- Belum, nanti sore.
Indonesians don’t typically answer with ya/tidak here.

Is kamu appropriate here? What if I need to be more formal or respectful?

kamu is neutral–informal and fine for peers/younger people.
More formal/respectful options:
- Sudahkah Anda menyampaikan…?
- Sudahkah Bapak/Ibu menyampaikan…? (addressing an older man/woman)

Do I need to add saya after salam to show whose greetings?

Optional. salam alone usually implies the speaker’s regards from context.
To be explicit: sampaikan salam saya kepada… or titip salam dari saya kepada…

Can I make this sentence passive?

Yes:
- Sudahkah salam disampaikan kepada orang tuanya? (neutral passive)
- Sudahkah salamnya kamu sampaikan kepada orang tuanya? (object-fronting; mixed register)
Passive emphasizes the action/result rather than the doer.

Is it orang tua or orangtua?

Standard spelling is two words: orang tua.
You’ll often see orangtua in real life; many style guides still prefer orang tua.

Can I omit the preposition and say sampaikan salam orang tuanya?

Don’t omit it here. Without kepada/ke, sampaikan salam orang tuanya is likely read as deliver the parents’ greetings (i.e., the greetings belong to them), not greetings to them. Keep kepada/ke to mark the recipient.