Ah yes

The most popular threesome Sanscest ship in the fandom...

Creammare

I'm not with it, nor against it

I like Crossmare and Cream, but what brings it down is Dreammare

But it's pretty much the only threesome I respect, due to the constant Crossmare vs Cream vs Dreammare

I'd give it a 5/10

Pretty much indifferent about it all, but I guess it could work, because all the ships have chemistry

Update:
I don't prefer the ship however. A threesome doesn't fit the characters, plus I'm not a fan of threesomes, I only do it for jokes. It's fine if you do, but I personally hate threesomes itself, it's just kind of wrong, more of a one nightstand kind of thing rather then a long term relationship.