How does replaying a chapter work ?

[53 & still gaming]

I now have finished Chapter 2 and started 3.
However, I want to replay the pine cone scene in Chapter 1 for the achievement.

I see how I could start a past chapter and subchapter.
BUT the game tells me that "the progress of a different chapter would be lost": do I lose my chapter 3 if I continued ??

[Boboscus]

If you played through chapter 3 you would lose progress in the subsection you finished I believe, but you can then go back to replay chapter and pick subsection.

[Arrogant Player]

50 year olds worry about achievements? ♥♥♥♥♥♥♥ kill me

[53 & still gaming]

I am a completionist --\O/--

[kristijan.123]

You only loose progress made in sub-chapter that you are in, so if you only started chapter 3, you would be back at the start, once you finish what you need in other chapter, if you play through like half way, than some progress will be saved and won't be lost