Due to multiple bugs in the Fabrication API, I would say this isn't technically possible in a consistent way using the API in its current state. If you know lisp, then you could gain access to 4+ decimal precision (using List Setup in the right click) via 300 dxf group codes. From there you will have to analyze every part either in the model or in a selection against your baseline part manually creating the associations; which i've done and its ugly. Even that creates a scenario that still cannot be solved; O-Lets. Those you WILL need to use the .Net API and approach it from the basic AutoCAD entity to get its grip point that resides along the pipe centerline. Honestly you could do the whole thing using the Entity grip points because there are no native logical associations with or without the Fab API. CADmep is the best MEP sandbox ever created and thats why people like me can make it do all kinds of things it was never intended to do, but it almost always involves a long hard road...