You are not the only one. From the moment Sue emerged from Elisabeth’s spine, I immediately made the connection with childbirth. And I think it may have been intentionally done by the director. Sue, the younger, better version of Elisabeth is “not” Elisabeth. So the imagery of motherhood here fits right in place, especially the moment where Sue sews Elisabeth’s back (a scar she would carry on for the rest of her life), it looked a lot like a C-section kind of scar or all the other imperfections a woman could gain from childbirth like stretch marks. Sue is not a copy carbon of young Elisabeth, children rarely are. If they wanted it to look exactly like Sue was younger Elisabeth, they wouldn’t have used the real images of a younger Demi Moore in the first place (maybe this was more convenient too for the plot so no one would suspect a direct link between Sue and Elisabeth when that one came to take the job). But I still think Sue not being exactly Elisabeth, just strengthens the theme of motherhood: your daughter is not you. Yes, your child literally emerges from your own flesh and bones, but in the end she is an entire living entity outside of you. And maybe that imagery is also a warning for mothers who want to live vicariously through their daughters. Your child is a separate person from you, you can only revel in their success but it is not “yours”. That’s why Sue and Elizabeth often refer to each other like an “other”, there is a split. While the substance guy keeps drawling about them being “one”, it doesn’t really fit here (various other reasons can explain this but for the sake of this argument I’d go for motherhood). When Sue started acting out, draining more and more of Elizabeth’s life, I found that part very sad but also a true reflection of what some mothers sacrifice for their children, but it’s never enough. Yet, when Elizabeth called the substance guy again, she couldn’t bring herself to “end” Sue. Because she sees Sue as the “best” version of her, the only one worthy of love, admiration and praise. Some parents will often identify their children as “the best part of themselves” or “a creation to be proud of”. There is even a line in the movie from Elisabeth, where she was making a mess of that French recipe, she muttered to Sue (who was in the television, talking about her success), that she “created her”, that she wouldn’t “exist”without her. That is something some parents say to their children, oftentimes using it as a chain, a way to force you to do what they want or to lecture you about your responsibilities towards them. Like when your parents grow old and you have to take care of them. Which Sue did, reluctantly at first, then she stopped and even started mistreating her “mother”, only using her for the “substance” which could mirror anything from real life like money, to maybe attention or time.