Yeah I know some do that, but I don't think it's the case this time, however as you said yourself, this is kinda a dangerous path Ocean is taking, because he can end up making these characters show up here who has relations to the others in WIAB, which would make us feel like the choices we make doesn't mean squat in WIAB.. Like if she indeed is Miru's and Will's but in your case you dumped her, then how the fuck did she get born??
I love both games, but I actually think this idea of making two games in the same universe with characters in relation to each other, should be made subsequently, not simultaneously, since we can't import the "actions/choices" we made in the past, so it influences the story of the future.