Hi @JohnThomas, thanks for the clarifications.
looking at your first post (and code), it was unclear to me if you sticked already to the information we discussed, time ago, about spline generation and child objects (GetVirtualObjects or GetContour) but looks like that your full code was already capable to return the desired output.
Searching more in depth in Cinema 4D code, I've stumbled across a piece of code about the dynamic tags, mostly related to performances reasons, that ignore tags on virtual objects unless they have been created by cloner/fracture/particle emitter/array. This explains the reason of your plugin failing to retrieve the proper geometrical data due to the dynamic tag being ignored .
However, as you've experienced already, removing the
OBJECT_INPUT flag makes Cinema 4D thinking of your plugin not using virtual objects from children and, consequently, having the dynamics tag ignored no more but still letting you use that data from objects being nested under your plugin.
Below a simple example obtained by implementing BaseObject::GetContour, BaseObject::GetVirtualObjects() and registering the plugin as
OBJECT_GENERATOR | OBJECT_ISSPLINE. This represent a workaround to the actual system limitation so corner cases which might be hard to fix might appear on more complex setups.