Not a mod, but I'm thinking that since you're okay with Aaeru/Neviril/Paraietta, that's probably the only way you'd need to nominate it, right? You can just put the other information in your optional details so your writer knows you'd be fine with either a complete triangle or a V-shape.

(If you definitely wanted to NOT get Aaeru/Paraietta, my guess is you'd just have to nominate the other two pairings individually, and then put it in your optional details that you're happy to see both of those pairings happening at the same time.)