Would it not be possible to "Tag" the voxels and elements that are the product of a blueprint as being a copy. And then exclude marked voxels from being blueprinted if you don't own the rights ... and thus Like Lethys suggests "it would have to be completely rebuild voxel by voxel.
this could/ would mean that
- each play would create a unique tag based on player id, date and blueprint (+version),
- players can alter/ update there own blueprints without worry, (buyers will be able to see the version of blueprint)
- the blueprint will be back traceable to owner,
- marked as master blueprint or authorized copy ( as is intended by the devs)
and to make it harder to reverse engineer, it could be implemented that no warning wil be given if there still is a "Marked" voxel / element in the to be created blue print that were excluded from the new blueprint so just replacing blocks of the build, block by block will get a lot harder to manage on larger builds.