If I understand your question correctly, you can still get on the Alison path even if you miss out on the first opportunity (Shine).
To do that, you need to pursue Alison at every opportunity you get after Shine. This means seeing her for dinner and using the willpoint and also pursuing her in Blaze . Do that and she will stop seeing Jeremy. You'll know because in ch 6 Alison tells Ian she has only been seeing him and has not seen Jeremy in weeks. Another confirmation is in ch 7 where Jeremy tells Ian Alison has been ignoring him or something like that. At this point, like Mares said, Ian would have received one photo from Jeremy only and no videos.
As for missing out on the second opportunity, if Ian had already fked Alison in the first opportunity (Shine), even if he misses out on this second opportunity (either by seeing Lena and Holly or just kissing Alison and not spending the willpoint), Alison does not fk Jeremy. She basically remains "faithful" to Ian provided that Ian pursued her back at Shine. So again, the Alison path remains open.
If however, Ian did not pursue Alison back at Shine, Alison will fk Jeremy regardless of whether Ian took up Alison's dinner date or not. Again this is all based on memory (also on ch 7 not the revised version) so I might need confirmation on this

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