Every art and every practice has a mainstream and an avant-garde section. Every practitioner has an idea of where the boundaries are. Most are in the mainstream, which is why it is called mainstream. The further a question is from mainstream the fewer practioners have experience.
The basic answer to the fusion question is you might make a planting that looks good. Some would say give it a try. There isn't a lot more to say.
There are a lot of guidelines for single trunk design and few for fusion, which us why there are so rew answers here.