1) Solid chapter overall, though there are a few details that could be improved upon. Especially in the middle part, the overcrowding of very similar or outright same expressions took away some joy from reading experience. It's a long installment, so proofreading must have been tiresome, but it would greatly benefit from some editorial changes. Pay special attention to words like 'softness', 'firm', 'steady', 'maternal', etc. and constructions of the form 'X yet Y'.

2) Who is the 'real' Stephanie? I honestly do not know. We know some facts from her life, but too little in general to contrast it with what she is to represent as Ruby. Consider some flashbacks in future chapters to show (not tell!) who she was before and how she approached life. Right now the forced transition has less weight from reader's perspective than how it most likely feels from hers.

3) Kinks are nice, but they should never shroud the story (I am not speaking for the purely erotic one shots you can find even on this site - most of which I find annoying and empty). In my view: intricate plot > character development > worldbuilding > kinks in terms of importance for an ambitious novel(la).

4) I won't comment on the plot, as I am not the Author of this tale. Attempting to insert oneself and one's ideas into another's opus is mostly detrimental to the final result as it loses cohesion and the beauty of singular vision. So I can only write this: do not listen to ANY who want to tell you where your story should go. This tale belongs solely to you.

As the arc comes to an end, a review is in order. I have to admit, your tale is one that is both exciting and extremely uncomfortable to read at times (and it  is not even due to kinky/potentially disgusting stuff). You are very good at creating tension, keeping readers on edge and mixing gentle and absolutely dehumanising tropes. I have seen a fellow reviewer draw parallels between your story and the massive and still unfinished one by WriteofPassage. I can see the similarities in concepts and general ideas, but I am even willing to argue your vision is much more dystopian in nature:

1) In "To Break in a Pet" (TBP) the sosciety is generally supportive of people affected by genetic trait, they live with their families/loved ones and while definitely challenged in everyday life they are recognized as humans and are free individuals. The villlains are a group of magnates, immoral to the core and operating outside of official institutions through briberies, extortions, bullying and intimidation. Basically capitalist elites with facsist tendencies. The protagonist fights for her freedom against a clear enemy and has hope - despite the fight taking toll on her psyche.

2) Your story depicts a sosciety that normalises dehumanisation of its members on reguar basis. It is incredibly self-destructive as a demi may be born in any family and their condition is determined after many years. Then all the emotional investment and bonds formed and nurtured  are supposed to be cut and a demi ceases to be person, they become a commodity to be sold and bought. Moreover, it is expected for their families to sell them immediately! This is one of the bleakest scenarios I have seen, one that deprives demis of hope alltogether as their enemy is the whole country/world. Stephanie does not have it even the worst, she's probably in the top one percent of most fortunate - yet even her fate bears the same marks of hopelessness. This setting does not even need violence to exude a truly dark aura.

3) Even the government agency members, responsible for demi affairs, show total nonchalance (admittedly, they are not tasked with protecting demis but rather the interests of owners). Agent Estevez is not particularly cruel, but she just does not recognise Blackie as a person, merely an  accessory meant to be used as she sees fit. He claims he is happy, but is it even close to happiness? The way I interpret it, he is a broken individual, who does not believe in better future...

As to the chapter itself, some minor pacing issues, but a great job nevertheless. Cannot wait for the second arc...

But I need to say, I think it's not all that great that Stephanie's character development comes down to basically brainwashing. If she's simply made to have no opinions of her own, mind forced to go along because of her biology, this takes a lot of the immersion and makes all of her thoughts and experiences quite a bit flatter. 

Also, the agent could at least look into Heather's demi, if she wants to see how the system doesn't work.

She seriously should, at the very least, have negotiated a safe word for things that should truly be off-limits/would leave her crying. 
As far as it was understood, there was the chance to reverse the transaction if something comes out later about them not fulfilling the terms of ownership,.

Maybe Heather's name should've been dropped to make the callback to the first chapter easier.

Is the omega class inspired by "to break in a pet"?

It's nice start, hoping to see some action soon 

I feel like Roxy should've added to ease the new tiny into the situation, and regarding sex, pay attention to their experience on this matter.

Not everyone is a professional sex worker, and with someone who was a minor, not too long ago, they'd have to pay double attention not to go too hard too soon.

Especially if they want to establish a degree of trust.

Now I'm very interested in the next chapter.

Will she actually be genuine and capable of showing compassion for someone who got the equivalent of a death sentence?

For now, she seems to be highly based on a whim induced by her friend, and mostly wants it because it's trendy.

Yet it would be nice if she could actually empathize and maybe also think of things that could make Steph genuinely happy (based on the things she learned about her), and make her feel like a person, instead of forcing everything onto her, after tricking her mother into believing that she cares.
Obviously, still in exchange for getting her way at times.

Interesting concept so far...! 

Very interested in where this goes and who gets her.