how skeleton modelling is done in pro-e?
It is actualy quite easy.
First you have to add skeleton model to assembly, this is done via Create/Skeleton
Then you simply edit the skeleton model (fist feature in your assembly tree structure).I would advice you to make the skeleton as simple as possible, and make the constrains so, that you can edit them quickly.
Then it is probbably the best practice to use copy geometry feature in your parts, where you copy references from the skeleton model, where you initialy align part and skeleton default CJS.
The bennefit of this is that you can very quickly initialy asemble everything to default CJS in your assembly, but still if you won't you can than later change every part references as you wish.
Also you stil have complete control of every important dimensions in your skeleton.
Another benefit is that you can then freely delete, add, drag and drop different parts freley from one subasembly to another, without the fear, that it would ruin your tree structure, as all the parts have all references conected to skeleton model.