Totally agreed they should be Melodie's project. I like the idea that they are the next project upon Allison's... graduation to servitude essentially. (Spoilers related to latest Chains comic.) What's even better is they create a sisters-dynamic with all the complications that come with that.
Identical twins are an interesting dynamic if handled realistically too. There's a sort of divergence as each seek ways to identify with "them-self" to a tolerable degree. Yet there's no denying they're an inserparable team, especially when that partnership is built from chains and servitude. (With each bearing a different angle when navigating their tricky station in life.)
I can already see some of that just in their pose. One is more affrontive and confrontational, while the other is more meek. But when one is protective or defencive, the other seeks other ways of resolving sexual encounters and chores. Yet for that difference, there's the undeniable fact that each know EXACTLY what another if feeling throughout their frequent and systematic bouts of sex. They have the exact same bodies, so they'll know exactly what any given act feels like just from sight.
Then there's the sex itself. (and yes, I'm a bit excited here! heh!) I can only imagine how creative they can get when you've got a similar-ish mind in two bodies instructed to satisfy someone.
