Hi Alina,
You can refer to this post regarding the general usage of the Subworkflow (SQL) action:
https://community.webcon.com/posts/post/starting-workflows-in-webcon-bps-actions/76
It uses an item list but in you case you only need to start always exactly four subworfklows. Perhaps there are four "role" people fields and each role should take care of its task.
In this case I would do something like:
Select 'RoleA' as Responsible
Union
Select 'RoleB' as Responsible
Union
Select 'RoleC' as Responsible
Union
Select 'RoleD' as Responsible
Where the responsible field is a field taken from the objects tab. The role is the field value from the workflow instance.
In case your subworkflows have a negative ending step and all subworkflows need to be finished, regardless of positiv or negative ending, before the parent workflow moves on, you need to use the advanced configuration.
Advanced wait for sub workflow step configuration
https://alterpaths.com/wait-for-sub-workflows-step-advanced-configuration/
Best regards,
Daniel