Hi,

i want to create an immovable milestone and am not sure if this is possible with the current features.

Use-Case, as visualized in my attached png:

I have one parent-package "Parent1" with 3 sub-packages, the last one is "Sub1".
I also have one milestone "MS1", which follows (or "needs") Parent1.
I want to fixate MS1 on a date, so that it is not moved automatically.
When the end-date of Sub1 is changed to be after MS1-date, OpenProject should prevent this and show a relationship-violation (or some other error as in other cases).
The date of MS1 should still be changable but only by users and not automatically.

I tried every possible relation-type and none of it worked.

Is there a way to accomplish this with already existing features (I'm using the free version of OpenProject, if that matters)?
If not, i would create a feature-reuest. Just want o make sure i am not missing some way.