Can't import (multiline) text within a template

[0cv]

I'm using the syntax !? $import('name_of_the_file.yaml') to import a yaml file into my (yaml) template. Except that I'd like that this imported file be treated as text rather than yaml:

template.yaml

Key1: Val1
Key2: !? $import('related.yaml')

related.yaml

a:
  b: 10

Once compiled:

Key1: Val1
Key2: 
  a:
    b: 10

Whereas I'd like:

Key1: Val1
Key2: |
  a:
    b: 10

I've tried various options such as:
1- adding a simple pipe | and wrapping the import

Key1: Val1
Key2: |
   !? $import('related.yaml')

But this ends up as

Key1: Val1
Key2: "!? $import('related.yaml')\n"

2- Trying to indent more or less !? $import('related.yaml') result in an error

I'd not mind adding this pipe manually through some Yglu syntax, but I couldn't figure out how to do it (whether it's possible?)