Lack of particles in songs

Question

I was trying to translate this song, it was all going well until I stumbled upon this line

二人迷わぬよう歩いていけるたった一つの道標

I am having a hard time spliting the words correctly I feel like it either is lacking some particles or commas, I'm not really sure... What I could come up with so far:

二人(が)迷わぬよう - It's like both do not hesitate.

歩いていけるたった一つの道標 I can only walk one more signpost. (lol sounds weird, I might be wrong)

So maybe the whole thing should rather be structured like this?

二人(が)迷わぬよう、歩いていけるたった一つの道標。 It's like both do not hesitate, (but) I can only walk one more signpost.

Thanks in advance!

Ps: This is the last line of one paragraph of the song, so it's a ful sentence which should hold some meaning alone, also the previous line is talking about other stuff aswell.

EDIT: The whole paragraph of this song is this:

一枚一枚増える色の違う写真めくる様に

伝えたかった事は今も昔もずっと同じままだよ

二人迷わぬよう歩いていけるたったひとつの道標.

Answer 1

The critical problem here is wrong parsing:

［二人（が／で）迷わぬよう（に）歩いていける］たった一つの道標
(It is) the only signpost [that enables us (two) walk along (in pair) without(=the way not) losing our way]

It's a typical "gapless" relative clause explained in this topic. The literal translation would be "the only one signpost that/where we can walk along..." but it doesn't make sense in English, I guess. This construction tells "signpost" has something to do with "we can walk along without being lost", thus results in the translation above.

For lack of particles, you can insert が or で after 二人 (it's ambiguous whether it means "we two" or "in two of us"). You can also add に after よう, but it doesn't change the meaning in this context.

Answer 2

「二人迷{ふたりまよ}わぬよう歩{ある}いていけるたった一{ひと}つの道標{みちしるべ}」

First of all, this is only a relative clause, not a sentence of any kind. Everything in front of 「道標」 modifies 「道標」.

If a somewhat long phrase ends with a noun, there is a big possibility that it is a relative clause and not a sentence.

Second of all, even though no particles are "lacking" in the first place, let us add a couple if that helps.

「二人（が）迷わぬよう（に）歩いていけるたった一つの道標」

If one blindly believes that this is a sentence, trust me, one's translation is bound to look at least weird or awkward because it is not a sentence to begin with. Since it is a relative clause, a good TL will have to start with:

"the only road sign (← 道標) that/which ~~~~~~~~~~"

My own TL would be:

"the only road sign that enables the two of us to continue walking without getting lost"

Answer 3

Could this mean the only signpost which both people can reach by walking without hesitation? And the insertion of が looks right.