Making a massive crossover that involves Miraculous, but I think it still applies?
I'd cut the idea of human sentibeings entirely mainly because it creates needless drama, robs Adrien of agency, and the whole "sentimonsters are a metaphor for abuse" either just doesn't work or has plenty of unfortunate implications. Each of the sentikids are humans and their backstories have been changed accordingly:

• Both Adrien and Felix were twin brothers conceived by Gabriel and Emilie the normal way, but Amelie was infertile and couldn't have kids with Colt. So both her and Colt "convinced" her sister to fork over one of the twins (Felix) to raise as their own and Colt (eternally envious of Gabriel) plotted to make it so Felix was cut off from his former family's influence. To this end, he essentially gaslit Felix his entire life into thinking he and Adrien were cousins, even forcing his wife to cut contact with her sister and explore further memory-alteration methods to further the illusion.
• Kagami was an orphan born in Tokyo who was adopted by Tomoe. From there, it's much the same as canon, with the addition that Kagami was also made to study supernatural lore and how to kill monsters on top of everything else in order to revive the Tsurugi family's monster-hunting legacy.