There is an officer Reichs kokarde with the center and 2 smaller holes for sale right now on A of K. To me this is designed for the M91 post and prongs to go through the kokarde and into the helmet.
That’s correct. But according my informations this type came up for officers around 1915. Nevertheles, I have to correct the source where I have my informations from. I wrote an Essay about cockades for myself from various sources, when I started interesting for Pickelhaube. Unfortunately I lost the source and thought it was from a french book too, where I got other informations from, but it was an entry in a French Forum of our dear member
clovis57. Hope he can tell us if he knows a book where the informations are from

Here is the Link where I found the informations
https://lagrandeguerre.1fr1.net/
And this is my translation from the part acc. Model 1915:
At that time there were 5 different models (only the last two are M15 creations):
- Enlisted men: cockades as from 1891 with M91 mounting hole (since 1895 with a reduced diameter of 48mm).
- NCOs with portepee: As 1891 with M91 mounting hole and single metal ring in silver or gold.
- Officer-cockades for property helmets existed from 1871/99.
- Officer-cockades with M91 mounting hole.
- Officer-cockades with a small mounting hole and 2 small opposite punched holes for the pins of the M91 buttons with which they are locked .