Learn Hardcore Indonesian: Dia mirip kakak perempuan saya yang tinggal di utara, menurut Ibu. - She/He looks like my older sister who lives in the north, according to Mother.

Yang introduces a relative clause (who/that/which). In this sentence, yang tinggal di utara modifies the immediately preceding noun phrase, kakak perempuan saya. So it means “my older sister who lives in the north.” You can’t drop yang the way English sometimes drops “who/that.”

Could yang tinggal di utara be talking about dia instead of the sister? How would I say that?

As written, the default reading is that yang tinggal di utara describes kakak perempuan saya. To make it describe dia, move the relative clause next to dia:

Dia yang tinggal di utara mirip kakak perempuan saya.
Or add commas for a nonrestrictive feel: Dia, yang tinggal di utara, mirip kakak perempuan saya.

Does mirip need dengan? I’ve seen both mirip X and mirip dengan X.

Both are fine:

mirip + noun is common and natural: Dia mirip kakak saya.
mirip dengan + noun is also correct and can feel a bit more explicit or formal: Dia mirip dengan kakak saya. You can intensify with sekali or sangat: mirip sekali (dengan) kakak saya.

Can I say Dia adalah mirip...?

No. Adalah is used mainly for equating nouns (e.g., Dia adalah dokter). With adjectives or adjectival predicates like mirip, you don’t use adalah. The correct form is Dia mirip…

Does dia mean “he” or “she”? What about ia and beliau?

dia is gender-neutral and can mean “he” or “she.” Context decides.
ia is a more formal/literate variant, mostly used as a subject: Ia mirip kakak saya.
beliau is an honorific third-person pronoun for respected/elder people: Beliau mirip kakak saya (polite/respectful). If you need to show gender, specify it (e.g., pria itu, perempuan itu) or use the person’s name.

Is kakak perempuan saya the most natural way to say “my older sister”? Could I just say kakak saya?

kakak saya = my older sibling (gender not specified). Very common; context often makes gender clear.
kakak perempuan saya explicitly says “my older sister.” Use it when gender matters. For “older brother,” say kakak laki-laki saya; for younger siblings, use adik (e.g., adik perempuan saya).

Can I use the possessive suffixes, like -ku? For example, kakakku or kakak perempuanku?

Yes:

kakakku = my older sibling (gender unspecified).
kakak perempuanku = my older sister (explicitly female). These are a bit more informal or personal than kakak perempuan saya. Choose based on the register you want (formal: saya; casual: aku/-ku).

What exactly does menurut Ibu mean? Why is Ibu capitalized?

menurut Ibu = “according to Mom” (as an opinion), if Ibu refers to your own mother as a proper name/title.
In conversation, Ibu can also be a polite form of address for an older woman, so menurut Ibu could mean “in your opinion, ma’am.” Capitalization: kinship titles like Ibu/Ayah are capitalized when used as a name or form of address (e.g., Menurut Ibu, …; Ibu Sari). Lowercase ibu is the common noun “mother.”

What’s the difference between menurut Ibu and kata Ibu?

menurut Ibu focuses on someone’s opinion or judgment: “According to Mom (in her view) …”
kata Ibu introduces reported speech: “Mom said …” So use menurut for opinions and kata (or bilang) for what someone literally said.

Can I move menurut Ibu to the front? Is the comma necessary?

Yes, placement is flexible:

Menurut Ibu, dia mirip kakak perempuan saya yang tinggal di utara.
Dia mirip kakak perempuan saya yang tinggal di utara, menurut Ibu. A comma helps readability when menurut Ibu is detached from the main clause, especially at the end.

What does di utara mean exactly? How is it different from ke utara? Do I capitalize Utara?

di utara = in the north (location).
ke utara = to the north (direction/motion). Capitalization:
Lowercase utara for the compass direction in general: di utara.
Capitalize when part of a proper name: Jakarta Utara, Sumatra Utara. You can be more specific: di bagian utara (kota/negara itu), di sebelah utara Jakarta, di Jakarta Utara.

Can I use seperti instead of mirip?

Sometimes, but they’re not identical:

mirip emphasizes resemblance, often visual: Dia mirip kakak saya (they look alike).
seperti means “like/as,” and often suggests similarity in manner, role, or behavior: Dia seperti kakak saya (he/she is like an older sister to me). For looks, mirip is the safer choice.

Could I replace tinggal with something else?

Yes, depending on register and nuance:

menetap di = to settle/reside (more formal): …kakak saya yang menetap di utara…
berdomisili di = domiciled in (very formal/official): …yang berdomisili di…
bermukim di = to reside (formal/literary): …yang bermukim di…
berada di = to be located in; use for location rather than residency: …yang berada di utara… (okay if you just mean “located in the north,” but not necessarily “lives there”).