From what I learned, you have to make the two characters have feelings for one another, interact with one another, have full interest in one another, and make it clear that these two will end up with each other in the end so that at least the majority of the shippers will tolerate it even though it is not their preferred ship but it makes sense and it's obvious to them.
If we don't make it clear, they will explode in the media, sending death threats, shipping wars, and pulling out all kinds of nonsense on why should they end up with each other. Pure chaos.
Also a shipping of incest, and age gap is a big no no.