You do realize just how much work you've described for a single side-girl scene, right?
First off, it has only been a few months after MC could impregnate Vall - she would be visibly pregnant, much like Aurora/Isis are. That would mean LM has to create a separate render for a pregnant Vall for the routes on which she is pregnant - and since that is only 1/3 paths with Valleria, I don't think it's happening. More likely is, this scene is for those that didn't execute Valleria and/or saved her from judgement only.
Maybe he surprises us all with those preggo variations, but then that's a lot of work spent on a side-girl; Rosa still hasn't even been shown or mentioned, or Spring - and even the wife of that villager that let us impregnate his wife & daughter on the way to the West was not made pregnant in a variation.
She's much farther along than Isis and Aurora. Elis can get her pregnant in the very first encounter. Of course, you can have another chance later, but I'm pretty sure she would still be farther along than Aurora and Isis.
Also, you do realize all of Val's encounters are like that right? If it was too much work, her past scenes wouldn't exist. What I'm mentioning is already in the game.
When you encounter her in the forest. You either rape her, impregnate her, or let her go. There's not a complete separate scene creation just for said encounter. Excluding perks, but that wouldn't play part in the later scenes.
When you're in the city with Alaina and free her. You rape her, impregnate her or talk about her new freedom. This is once again in the same area. He bends her over after Alaina leaves and fucks her. Alternatively, he just chats with her on the steps, if you're on the love side of things.
Under the assumption that the same pattern happens. It would follow the same logic as the first two Val scenes. You either get the love scene, rape her or get a blowjob (if she's still pregnant). All of which should happen after Alaina leaves.
That's how I see it though. I don't get how her being a side girl would affect this process when the dev has already did it twice now. The only difference would be if Val is pregnant or not. In which case, he could just outright skip the sex scene altogether and just add dialogue to the scene.