HGR is very literal about his GF/Miller roles (as it should be tbh). You can bet that the Miller would not look out of place on the scumteam, rather than just being a 'shady, suspicious' character, and the potential GF is someone you wouldn't expect at all. Someone more familiar with Touhou can chime in here though, because my knowledge begins and ends with Mercs (and Drak power rankings).
Drak's also right about the potential for 3rd parties, but it's not something I'd want to worry about until I have reason to. I realise that by then it might already be too late, but being concerned over anti-town that might not even exist is like the mafia equivalent of being scared of monsters under the bed.
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"Eet's game time..."