It sounds like the hierarchy you would want is a package group of package groups. However, packages groups cannot nest each other in Blesta. You could only have one level of nesting, which is the package group and the packages inside that group.
With that said, you can accomplish the behavior from your example (i.e. 1 level of nesting) using the way some templates display package groups on the order form.
For example:
Create an order form
Choose the template "Wizard Boxes". You could also use "Wizard Slider", or the respective AJAX equivalents.
Assign 3 package groups to the order form:
"Beginner"
"Intermediate"
"Advanced"
Each of those package groups should have multiple packages assigned to them, respectively, so the customer can choose the package they want to order from that group.
Visit the order form (e.g. /order/main/index/orderformname)
You will have 3 package groups to choose from: "Beginner", "Intermediate", and "Advanced"
Once you choose one, you will then see a list of all packages you can order from that group
I think that will be the closest native support for your use case.