Ouch, this may be heading down a confusing path that even my own insanity may not be able to comprehend to say the least.
Although, to work with ya here I do have a thought that could work in relation to 'splitting the beasts' And that would be Yin/Yang parts of the beast as shown by Minato in his attempt to seal the Kurama into Naruto. I'm not entirely sure but does this mean that the whole time Naruto held the Kurama, only half the beast was truly in Naruto? I have no idea but in relation to that, Minato and Naruto were both able to perform their own tailed beasty mode thing so It could work. The specialty cases we have now can be put aside but for the future, should a host truly wish to split the nature of yin and yang tailed beast chakras I guess they can and have two hosts of the same beasts only on a lesser scale. The most epic tag team duo, given that in most cases the split would happen due to opposite heads so those who work in unison with their counterpart may be indestructible! Of course, someone will complain about something and something again. I mean hell, the thought of having more than one of the same jinchuriki is quite bizarre already though....
I honestly think the 3 cases that have already split should literally fight for the other half. >>; <<; >>; Squash the beefs and move on. I mean isn't that the point of holding a beast, to fight for it? I dunno I always thought of the beasts as title belts and kurama being the wwe championship belt xD More of like a pride thing if anything, because some of these ninjas know how to be a biju without having a biju.