How to create "self" Rollup?

Summary:

Is it possible to create a Rollup for an object, but using SAME object as Related?

Content (please ensure you mask any confidential information):

We have a scenario where one Opportunity is parent, and other is child.

We have a DCL field in the child Opportunity to select the parent Opportunity.

Now we wish to create a rollup for opportunity, to show aggregated information of all children opportunities, however, in the rollup creation page, we can not select opportunity as related for opportunity.

Version (include the version you are using, if applicable):

25B