Merge global before_script code from included file with local before_script

Hi, In gitlab-ci.yml file I’m including another yml file which has global before_script code.
let say for example this code:

include:
- project: ‘SOME_PROJECT’
file:
- ‘common-ci.yml’

I want to inherit the global before_script from the included file, but also add more code to the global before_srcipt, WITHOUT override it.

for example this yml file
include:
- project: ‘SOME_PROJECT’
file:
- ‘common-ci.yml’
before_script:
- echo “some more global before_script code”

this cause the included before_script to be override. I want to merge both of them.
How it can be achived?