ATM and provided by default FreeCAD only has a little bit of cross document support, when using expressions. Everything else is basically still WIP and on the To-Do list. Modules like Assembly 2 and A2plus indeed do need such functionality and currently use this or that approach to support it.
I feel that in ideal scenario all of this would somehow come closer together. Link feature would be made available in the right click menu and as a command in Part workbench. By default it would create a lightweight representation of the geometry in the same or in an external document. Some limited subset of property customization would be supported, like color. Highly useful for adding standard elements from a library to assemblies. Property would exist for being able to turn such Link feature to "fat" mode. Basically Draft Clone alike and cross document enabled. Useful for things like cross document master sketch use cases and basically whatever you can think off ATM, difference being it's cross document enabled.realthunder wrote: ↑Tue Feb 05, 2019 12:08 amApp::Link can't do that, as it is provided by the core, and therefore has no knowledge of Part, PartDesign, or other features it can link to. But I do think a "fat" link is useful in many case, which is one of the reason I added SubShapeBinder in PartDesign. You can use it with or without a Body. In the latest release, it can directly bind to external object just like a Link, with no geometry copy by default. By flipping the "Partial Load" property you can make it copy the geometry instead, and effectively become the "fat" link you want. When you load a file containing the fat link, it will not load the external document. If you flip that property again, it will load the external document on demand.
In addition completely dropping the option, to have all the documents opened automatically, that likely makes sense too.
Now as for what will happen in real world. I don't know. Fingers crossed!