Just like Product Lines and Products, Features can have a hierarchy. Since Features have a Roadmap, they also have dependencies that should be allowed. BTW, this same logic would apply to Releases and Strategy since they have Roadmaps too.
|Release time frame|
This is possible today. Through the Actions menu on each record type in Aha!, you can create a link to another record. We also recently launched an interactive dependency map which allows you to visualize the relationships across records.
You can read more about it here: http://blog.aha.io/visual-interactive-dependency-map/