So, here is how I finally solved this. I have to point out however, that in my case I had to work with several files and proprietary modules that were changing all the time.
The best solution I found to do this was to use a FUSE wrapper to "link" colab to my google account. I used this particular tool:
https://github.com/astrada/google-drive-ocamlfuse
There is an example of how to set up your environment there, but here is how I did it:
# Install a Drive FUSE wrapper.
!apt-get install -y -qq software-properties-common python-software-properties module-init-tools
!add-apt-repository -y ppa:alessandro-strada/ppa 2>&1 > /dev/null
!apt-get update -qq 2>&1 > /dev/null
!apt-get -y install -qq google-drive-ocamlfuse fuse
# Generate auth tokens for Colab
from google.colab import auth
auth.authenticate_user()
# Generate creds for the Drive FUSE library.
from oauth2client.client import GoogleCredentials
creds = GoogleCredentials.get_application_default()
import getpass
!google-drive-ocamlfuse -headless -id={creds.client_id} -secret={creds.client_secret} < /dev/null 2>&1 | grep URL
vcode = getpass.getpass()
!echo {vcode} | google-drive-ocamlfuse -headless -id={creds.client_id} -secret={creds.client_secret}
At this point you'll have installed the wrapper and the code above will generate a couple of links for you to authorize access to your google drive account.
The you have to create a folder in the colab file system (remember this is not persistent, as far as I know...) and mount your drive there:
# Create a directory and mount Google Drive using that directory.
!mkdir -p drive
!google-drive-ocamlfuse drive
print ('Files in Drive:')
!ls drive/
the !ls command will print the directory contents so you can check it works, and that's it. You now have all the files you need and you can make changes to them with no further complications. Remember that you may need to restar the kernel to update the imports and variables.
Hope this works for someone!