How to create an Hammock task

I’m looking for creating an Hammock Task.

I’ve two milestones and I want to create a task between this two milestine with the duration is automatically calculated with the beginning of the first milestone and the end of the second.

How can I do please ?

This is not possible, sorry.

Ok, thx
Is there a way around it in your opinion ?

@GregB May this answer I posted be helpful to you, using a summary tasks containing the milestones.