I absolutely agree that Clara is the main focus for the MC. Since Amy and Betsy were among the girls you could fantasise about, they too have a bigger role to play than the others, but Clara is the central girl for the MC.
That Amy has her own development path is only logical. "Misfits" is more or less a prequel to "12 days", which means certain events have to take place to get that game situation for Amy. And these has consequences not only for Amy´s path, but also for those following her path. Since if you pursue Amy in Misfits, you have to develop towards the voyeuristic half-fag cuck Amy´s boyfriend in 12 days is. So in the long run, you can influence only some nuances about Amy, not the complete path.
Clara´s way as our girlfriend we can influence much more. We can push her towards sharing like in "the plan", cheating ourselves/being cheated on or being loyal to each other.
Additionally we have the daring/sexy dressing and public "mischief" path, which can be done regardless of the other paths. Doing this path and encouraging her raises Clara´s confidence, she dresses more sexy (and likes it to her own surprise) and starts liking showing off, doing some sexual stuff in public. For instance, loyal and daring path Clara get´s really hot and bothered at the thought of giving you in special a handjob on the beach in plain sight, no matter how many other people are there and nearly goes through with it.
Personally I think the daring dress path is more or less "canon", since the Clara in "12 Days" is nonchalant about showing off for personal or the gains of loved ones (hints of the stuff MC and Clara do at the garage to keep the workers), obviously likes doing some daring stuff in public, but unlike Amy, has a hard limit how far she goes. That also hints towards Clara still having her boyfriend/husband.
