In practice it is extremely difficult to manage assemblies of complex hierarchical systems in BDDs like this.
It is graphically very unstable, it is difficult to organise parents and children, and it does not make sense to
have children near or overlapping with elements belonging to different parents as shown in the spec sample.

Prefer instead my simple yet powerful (though non standard) recipe using <<composition>> Component
wrappers to graphically and logically group elements of assemblies recursively (see next image).

Image: