Logging time on tasks for external user

Logging time on tasks for external user

Hello, 

On some projects part of the work is done by an external company and i need to track those times too. 
Currently, I created a table in analytics where i enter manually the times linked to the task id. It is really painfull though. Is it possible to log time on projects for external user (only for tracking purpose, those users do not require any access to the tool). 
If it is not possible, can you suggest something more efficient than what i currently do with my custom table ? 

Thank you in advance for your help and happy new year !

Perrine