Learn Hardcore Swedish: Inte bara chefen utan också min syster håller med. - Not only the boss but also my sister agrees.

Because with a preceding negation (inte) Swedish uses utan (roughly “but rather/but also” in this pattern). The fixed correlative is inte bara … utan (också) …. Use men (“but”) when there is no such negation linking the two parts.

Example without the correlative: Jag ville gå, men jag var trött.
Correlative: Inte kaffe, utan te.

Do I need a comma before utan också?

Usually no. In a compact phrase like this, you normally write it without a comma:

Inte bara chefen utan också min syster håller med. Add a comma if utan starts a full clause with its own verb:
Inte bara chefen håller med, utan också min syster gör det.

Could I say utan även instead of utan också?

Yes. Inte bara … utan även … is a common, slightly more formal variant:

Inte bara chefen utan även min syster håller med.

Why is it chefen but min syster (no ending) even though both are definite/specific?

Swedish marks definiteness on the noun with a suffix, but possessive pronouns block that suffix.

Definite with no possessive: chefen (“the boss”)
With possessive: min syster (“my sister”) — not min systern With adjectives:
Definite + adjective: den stränge chefen
Possessive + adjective (no definite ending): min stränga syster

So is min systern ever correct?

No, not in standard Swedish. With a possessive pronoun, the noun stays morphologically indefinite: min syster, min chef, mina systrar.

What exactly does håller med mean and how do I use it?

Hålla med is the normal way to say “to agree.” Pattern:

hålla med (någon) om (något) = agree (with someone) about (something) Examples: Jag håller med. / Jag håller med dig. / Jag håller med dig om att det är sant.

Can I use instämmer instead of håller med?

Yes. Instämmer is a bit more formal/elevated. Your sentence becomes:

Inte bara chefen utan också min syster instämmer. You’ll also see vara överens (med) or tycka likadant in other contexts.

Why is med there? Could I drop it?

No. Hålla by itself means “hold.” The fixed verb–particle/preposition combination hålla med means “agree (with).” Keep med. Add om when you specify the point of agreement: hålla med någon om något.

Can I say hålla med om here?

Only if you add what you agree about:

Inte bara chefen utan också min syster håller med om förslaget. Without an explicit topic, just håller med is perfect.

Should the verb be singular or plural after “not only … but also …”?

Swedish verbs do not change for number. håller is used for both singular and plural subjects, so there’s nothing to adjust here.

Is inte here a real negation of the verb?

No. In inte bara … utan också …, inte is part of the correlative structure “not only … but also …” and doesn’t negate håller. A true negation would be: Chefen håller inte med.

How does V2 word order work here? Isn’t the verb supposed to be second?

It is. The entire subject phrase Inte bara chefen utan också min syster counts as the first constituent. The finite verb håller is in second position:

[Subject phrase] + håller
- med. If you front something else, you invert the subject:
Idag håller chefen med.

Can I use både … och … instead?

Yes, and it’s very common:

Både chefen och min syster håller med. The inte bara … utan också … version adds a stronger, contrastive emphasis.

Can I swap the order of the two people?

Yes. You can put the more emphasized item second:

Inte bara min syster utan också chefen håller med. In speech, the main focus typically lands on the second part.

Can I drop också after utan?

Yes, it’s possible: Inte bara chefen utan min syster håller med. However, utan också (or utan även) is the most idiomatic pairing and makes the structure clearer.

Where else can I put också?

Inside this fixed construction, it belongs after utan. In a simple clause you’d place också after the finite verb (or after the subject if the subject comes first):

Chefen håller också med. You can front också for focus (“Even…”): Också chefen håller med. For a very natural split version: Inte bara chefen håller med, utan min syster också.

What’s the difference between utan (but rather) and utan (without)?

They’re two different words that look the same:

Conjunction utan (used after a negation): Inte kaffe utan te.
Preposition utan (“without”): kaffe utan socker. In your sentence it’s the conjunction.

Any quick pronunciation tips?

chefen: [ˈɧeːfɛn] (initial sound is the Swedish sj‑sound)
håller: [ˈhɔlːɛr]
syster: [ˈsʏsːtɛr]
också: commonly [ˈɔkːsoː] or [ˈɔksɔ]
utan: [ˈʉːtan]
inte: [ˈɪnːtɛ] Primary stress typically on the first syllable of each word; in the whole sentence, speakers often emphasize också and the second noun phrase.