Is it possible to connect planner to milestones?

Sophie_Bruehl- Milestones creates a couple of Dataverse for Teams (D4T) tables in the 'current environment' (i.e. your Team). You will likely need to make at least 2 Power Automate 'flows' for it to work as you would like.

• When you create a task in 'Milestones' through the Power App
  • Trigger ➡ https://docs.microsoft.com/en-us/connectors/commondataserviceforapps/#when-a-row-is-added,-modified-or-deleted
  • Action ➡ https://docs.microsoft.com/en-us/connectors/planner/#create-a-task
• When you create a task in 'Planner' (Teams/Planner.com)
  • Trigger ➡ https://docs.microsoft.com/en-us/connectors/planner/#when-a-new-task-is-created
  • Action ➡ https://docs.microsoft.com/en-us/connectors/planner/#when-a-new-task-is-created https://powerusers.microsoft.com/t5/Microsoft-Power-Automate/ct-p/MPACommunity

Basically you'll need to create the 'flows' for all the CRUD (create/read/update/delete) operations so that whichever interface is used the desired effect will occur.

There maybe some samples in the https://powerusers.microsoft.com/t5/Microsoft-Power-Automate/ct-p/MPACommunity which you can reference.