Your question has been here for sometime without any responses. I believe that is due to the fact that you mistakenly believed "licensing" was the issue. On some level that may in fact be true but this practice area tends to be questions about driving licenses and professional licenses. I'm going to edit the Practice Area to "Trademark Infringement" where you are more likely to come to the attention of attorneys with experience in this very specialized area of law. Good luck to you.
I think you need to worry more about Montblanc trademarks and also about the law that forbids mislabeling. Actually there is a federal civil law that makes one liable for money damages and there is also a criminal law. There may also be laws in your state about labeling that yoiu will need to discuss with a PA attorney.
The problem is unless you take the markings completely off both components you will be confusing people about the origin of this hybrid.
Why not just sell the refills? “Enhance your low cost Pilot G2 with a smooth-writing, long-lasting Montblanc refill. (Not affiliated with Montblanc or the Richemont Group.)”
Licensed in Maryland with offices in Maryland and Oregon. Information here is general, does not create a lawyer-client relationship, and is not a substitute for consulting with an experienced attorney on the specifics of your situation.
I think you need to see an IP attorney that deals in patents as well as trademarks. The most likely solution for you is the kit. You should discuss the potential for patenting your conversion kit and selling the kit. In that I think you are on the right track. However, you need to both protect your right to do this so you don't get sued for trademark infringement and you need to protect you right to stop others from doing this, particularly Pilot. You likely got a call from a Pilot VP to sniff out whether you had applied for patent. If you haven't you are likely to get aced out by Pilot filing on this and claiming to have invented it, likely creatively documenting their conception prior to your disclosure to them. You may already be too late. You need to see a patent attorney like yesterday, my friend or this project could be dead in the water. You also made a big mistake mentioning the nature of your invention here on Avvo. Any good pen designer will be able to make a competing kit if they sense there is sufficient market.
I think you misunderstand the nature of the Mount Blanc customer. They think Pilot makes some great writing pens, but they want the more expensive pen as a status symbol. Your Pilot Pen with a MB refill won't have the requisite status. In fact, the status seekers won't touch it as it would label them as a wannabe on the cheap. Only those ultrarich who have no need to seek status and want to poke fun at wannabes might be interested.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.