I'd suggest creating the robes yourself using NifSkope. I just tried out some of Korana's CoV textures with a pregnant robe mesh from Children of Morrowind, and they work pretty well even without UV edits. You'll need to add an alpha property to the mesh for any dresses which have transparencies (and edit them to use something other than the Chest slot, e.g. Left Forearm or Left Ankle).
I wouldn't add transparent textures if I were you... The two robes are technically "robe" items, which means that many body parts are simply disabled, meaning that underneath the robes you don't have arms, or a chest, upper legs, etc. You could set them up as "shirts" in the editor, but then if you add transparency it could look weird if there is transparency around the belly area. The mod doesn't really change the chest body part, it's just that when you remove the pregnancy robe or shirt you're wearing at the moment you'll have a "shirt" that will be force equiped and will have the appearance of a naked belly. So if you equip a dress with some transparency, you will just have the normal, flat belly underneath, and it might look weird. You could get around the issue if you copy/pasted the appropriate belly meshes into the nifs of the dresses, but that might be a bit complicated to do if you don't know what you're doing and you could end up with clipping issues as they weren't designed with that in mind.
Not sure any of this makes sense. :blink: In short you should be able to use textures with transparency if you flag the robes as shirts in the editor and if you use textures that don't show the belly area. I think.
But yeah, apart from that you can slap many textures from other mods onto the robe meshes. They are NioLiv's meshes which I modified with her permission, and use the same uv mapping. They use CI's textures from her replacer to keep the mod "lore-friendly." Only thing you have to keep in mind is that each robe has 9 different meshes representing the different stages of the pregnancy and you have to modify all of them. I'm not sure how easy it is to create new pregnancy robes in the editor as they are scripted items, it's probably simpler to just modify the ones you already have.