Maybe, but my problem is less with the idea of Makoto giving birth that many times, and more with the nature of those characters
Akechi doesn't really fit into the "family dynamic", since he's Joker's rival; so here, he'd have to be like Joker's brother, or his ex, or something like that- though maybe him being an adopted child could work too. Probably around Yusuke's age.
Whereas with KaSumire, I have to figure out how to handle both Kasumi and Sumire; do I just have Sumire be their second-youngest daughter (only older than Futaba) and Kasumi just doesn't exist, or do I have both Kasumi and Sumire be there?
Maybe Kasumi, Sumire, and Akechi are all Shido's kids, but something happens that results in Kasumi dying/being removed from the family, and Sumire and Akechi are put up for adoption and adopted by Joker and Makoto?