Хоть бы официантка не забыла про добавку и вторую порцию гарнира.

In this sentence, хоть бы expresses a wish, hope, or anxious expectation.

So:

Хоть бы официантка не забыла...
= I just hope the waitress doesn’t forget...
= Hopefully the waitress won’t forget...

This structure often sounds emotional. It can suggest that the speaker is worried, impatient, or really wants something to happen or not happen.

A few similar examples:

• Хоть бы он пришёл. = I just hope he comes.
• Хоть бы дождя не было. = I just hope there won’t be rain.

So хоть бы is not literal here; it is a set expression used for wishes.

That is normal after хоть бы.

Russian often uses a past-tense form after хоть бы to express a wish about the present or future. So although забыла is grammatically past tense, the whole sentence means something like:

I hope she doesn’t forget.

This is a fixed pattern:

• Хоть бы он позвонил. = I hope he calls.
• Хоть бы она не опоздала. = I hope she isn’t late / doesn’t arrive late.

So you should not translate the tense literally here. The construction as a whole expresses a wish.

Because after хоть бы, Russian normally uses a past-tense form, not a future form.

So:

• Хоть бы не забыла = natural
• Хоть бы не забудет = incorrect

Also, забыть is a perfective verb, which fits well here because the speaker is worried about a complete event: the waitress might forget something.

So the pattern is:

хоть бы + past tense of a verb
even when the English translation is present or future.

Because the subject is официантка, which means waitress and is grammatically feminine.

In the past tense, Russian verbs agree with the subject in gender and number:

• он забыл = he forgot
• она забыла = she forgot
• они забыли = they forgot

Since официантка is feminine singular, the verb must be забыла.

Официантка means waitress, specifically a female server.

• официант = waiter / male server
• официантка = waitress / female server

In modern usage, some learners notice that job titles with feminine endings can sometimes sound more or less natural depending on the word. In this case, официантка is completely standard and common.

Добавка here means an extra helping, a refill, or an additional serving, depending on context.

In food situations, добавка often means:

• more of the same food
• an extra spoonful/helping
• a top-up

So:

не забыла про добавку
= didn’t forget about the extra helping / refill

The preposition про means about in a conversational sense:

• забыть про что-то = to forget about something

So the phrase literally looks like forget about the extra helping, but the natural English meaning is forget to bring the extra helping.

Both are possible with забыть:

• забыть о чём-то
• забыть про что-то

But про is often more conversational and common in everyday speech.

So:

• забыла о добавке = also correct, a bit more neutral/bookish
• забыла про добавку = very natural in spoken Russian

For a learner, it is useful to know that про regularly takes the accusative case.

Because про requires the accusative case.

So:

• добавка → добавку
• вторая порция → вторую порцию

Both nouns are objects of про:

про добавку и вторую порцию гарнира
= about the extra helping and the second portion of side dish

The preposition does not need to be repeated before the second noun. Russian often uses one preposition for a whole coordinated phrase.

Because гарнира is in the genitive case after порция.

Russian often uses this pattern:

порция + genitive
= a portion of ...

So:

• порция супа = a portion of soup
• порция риса = a portion of rice
• порция гарнира = a portion of side dish

In your sentence:

• вторую порцию is accusative because of про
• гарнира is genitive because it depends on порцию

So the structure is:

про [вторую порцию [гарнира]]

Гарнир means side dish.

Typical examples of гарнир are:

• rice
• potatoes
• buckwheat
• vegetables

So вторая порция гарнира means a second helping of the side dish.

It usually refers to the accompaniment to a main dish, not the main dish itself.

It sounds natural, conversational, and slightly emotional.

The speaker seems to be thinking something like:

• I hope the waitress doesn’t forget...
• Please let the waitress not forget...
• I’m worried she might forget...

Because of хоть бы, the sentence carries a feeling of concern or anticipation, not just a neutral statement.

So this is not simply factual grammar; it also expresses the speaker’s mood.