Thank you for a quick reply.
The STEP files we receive from our client are created in Solidworks. When we open them with Modo and export as FBX, then import to Maya, we have full logical hierarchy, which we can inspect in Modo as well as Maya.
The hierarchy is a logical scene organisation where all parts for logical collections of objects are gathered under a parent node, in structural parts. An example would be all parts of a wheel, door, lid or similar, which need to be able to move or rotate together. Naming is kept from the STEP file to Maya which is sometimes helpful if the CAD modeler has been a bit organised.
This hierarchy appears to be interpreted as blocks in Rhino. Blocks seem to have no hierarchial informatoin, but only provide some from of grouping of objects
I have tried exporting from Rhino exploded blocks as well as non exploded blocks,but when I import the FBX from Rhino in Maya the hierarchy is gone, and every part is in a flat hierarchy under one parent node.
Obviously this creates a lot of tedious work reorganising parts in new groups in Maya before the model is useful for our purposes.
The reason we are evaluating Rhino is because Modo produces inferior tesselation of the STEP files, resulting in bad shading and a lot of manual clean up work. The polygonal surfaces from Rhino look a lot better. Rhino also retains the correct scaling of the items, which is important, and Modo apparently does not.
So we would really like to use Rhino, provided we can keep the hierarchial information in the scene.
I have attached screenshots of the hierarchial tree in Modo and Maya as well as the Block Manager in Rhino. They are displaying the contents of the same STEP file.
I am hoping Rhino is capable of keeping this kind of information so we can make good use of it