Workload Chart/ Ressources View

Within our project Structure we have one "Admin Task".
Where we timelog our efforts for things such as Project Leading, Meetings, etc.

Everyone working on that project uses this task to track their time.

Recently we have tipped our toes into the Ressource View/ Workload Chart.

Here we were hoping that we could add everyone to that Admintask, so they can set up their weekly/daily efforts for said Project A.

For example I am not deep in that Project I only have 2h/week.
Meanwhile my colleague is the Project Lead and invests 2h/day.

I know you can have flexible times, but then you need to the edit them on a day to day basis.

We would be happy if we could split up a task's total effort on a per user basis:
I have a daily effort of 0.2hs and my colleague B has an daily effort of 2hs.

The only way we figured out so far to achieve this is, by creating task for each individual.
Also it's a bit weird to us that you have to be assigned to the task to have efforts on it...

Are there any workarounds for these issues, besides creating a task for each and everyone?