preserving hierarchy of a design

What do you mean by "preserve the complete hierarchy"? The complete hierarchy should exist in your design. If you mean it acts like a keep on every wire/signal in the design, there isn't anything that does that, but it would basically blow-up a design, bothin size and poor performance. Incremental compilation will keep all the pins of a hierarchy, and even that can cause problems if you do it too much. (To answer your question, I don't think there is, but also think it would cause serious problems. You had it working in X, so maybe it behaved differently there?)