Short answer: Nope. No way to do that with just a UTC edit.
Bonus pedantic, long, incoherent, TMI, tl; dr answer: You can't mod a UTC to include an asset that doesn't exist: there is only one 'nude' body model per race and gender for each possible appearance (with each equippable armour and clothing being a distinct race+ gender model); all human females (apart from the odd NPC with the 'fat' mesh) use the same nude/underwear model, reskinned or not, per your install. (In DAO, 'underwear' is not an equippable item, it's a whole-body texture for the *nuda* meshes.)
So, you'd first need to create a unique 'morrigan' nude body, a unique 'leliana' nude model, etc. and add them to the available assets. Then you could edit the UTCs to call your new models, rather than the default 'Human Female'.
For an idea of what adding additional unique models would entail, take a look at DarthParametric's children's 'clothing' modder's resource. (Can't recall the exact name offhand, but it should be here on the Nexus.)
(edited for spelling and extra pedantic goodness)
Edited by theskymoves, 30 June 2018 - 06:16 PM.