How do you spell the prefix?
The prefix “in” with the introductory words or adverbs is always written with a hyphen (sister, you think, etc.). In all other cases, this prefix is written together.
How do you spell “by”: individual cases
The presence of an adverb (including a pronoun) with the prefix “in” is not the only rule according to which a complex word is written with a hyphen. In the same way (with a hyphen) are written adverbs that end in: -y, -to, -ki, -to (bearish, humane, doggy, Georgian). When this condition is absent, the adverb with “to” is written together: (little by little, little by little).
However, it is worth distinguishing how to spell “in” with adverbs or cases when “in” is a pretext.
- Made (how?) In a new way (adverb).
- Walked along (which?) New (adjective) path.
In this example, “by” is a preposition, not a prefix. As a preposition, “by” is written separately with all the words.