Nutella_
It's something I've always wondered, and maybe you can use it, Kurama said that ten tails is just a massive mass of natural energy, while also being the progenitor of chakra, so it can be said that chakra comes from natural energy. Imagine having hagoromo's chakra isolated in one place, and then using natural energy to nurture it to increase its size. This way, can't one make six paths mode permanent?