protected virtual void OnParentChanged()

[michaelcsikos]

Sometimes I need to do something in a child object after the Parent property has been set, e.g. run a rule which may conditionally depend on something in the parent. When a new child is created we normally run the rules immediately in [Create], and then the Parent is linked up. The parent object could re-run the rules in the child, of course, but it would be nice if the child could simply override void OnParentChanged().

Or is there another way to do this that I've missed?

[michaelcsikos]

Oh, silly me. There's already a protected virtual void SetParent(IParent parent). Sometimes you just have to ask the question to find the answer yourself.