There's is a statement from https://martinfowler.com/bliki/DDD_Aggregate.html:
An aggregate will have one of its component objects be the aggregate root. Any references from outside the aggregate should only go to the aggregate root. The root can thus ensure the integrity of the aggregate as a whole.
What I have Order that has Items, and those items may be paid with different payments.
Should Include payments entities into the Order Aggregate, because otherwise it actually should have a link to inner Order's Item, not the whole Order? I don't get a little this Aggregate rule, and how it should be applied in the case.
My question: What Aggregates may exist in this case, can there be separate OrderAggregate, and say some other Aggregate that holds payments entities?