Hello ​@Amaury 
 

Yes, you can make this work in AdaptiveWork!

Just set up a Custom Action that runs when an action item is created or linked to a milestone. This action will automatically link the item to the milestone’s parent project.

You can use a formula like:
AddRelatedItems($ParentProject, $CurrentItem)
or
CreateRelationship($CurrentItem, $ParentProject.Project)

To set it up:

• Create the Custom Action on the Action Item object

• Set it to trigger when the item is created or when relationships change

• Use the milestone’s parent project to create the link

Hello ​@Archana D,

Thank you for your reply.
I have further questions.
Would it not be best to build a Workflow Rule rather than a custom action ?
Also when building a rule, i’m not sure i know how i can use the formulas you suggest. I have access to actions such as “Edit field” and then i can chose the “related to” field.
This is what i tried in an example below and it seems to be working:
 

My other issue is that although the rule works when i manually add an action item to a milestone, it does not when the action items are created as part of the project creation:
 

If it’s easier i can create a new conversation for this.