I think you meant CVPC is what you ordered.
Do you have a large investment in the CVPC pieces you are trying to put INTO the crosses in either time or money? Otherwise I think I would punt, and buy PVC pipe to replace the CVPC and go on that way.
BTW are the CVPC ones smaller or larger than the standard PVC?
If smaller wrap black electrical tape around a few times, works great for dust collectors, don't see why it would not work for a holiday display.
If it is larger, get a cap, drill right in the middle (maybe get a couple) so you can make a "mandrel" for the drill, and then you can sand down using the drill for power the too large pipe end to fit into the crosses you can find.
Alan