Can you dilute jelly?

[FurrySlipperBoots]

Like, if you add more water to it than the recipe calls for, it'll just get paler and less flavoursome right, but will still set ok? Or will it just stay runny?

It won't set.

It won’t set and it taste rubbish.

Jelly uses gelatine (or his tab in vegetarian) as a gelling agent. If it is overly diluted or frozen (broken down) it will not set properly or certainly taste fowl.