Ok, first of all, i think it's sadly too late for that and you will have to cheat. But here is what you can do to decrease eric's influence for each girl:
Mom:
- ask her to order groceries (↓5%)
- order groceries (↓5%)
- tell her you’ve order groceries (↓5%)
- ask her to buy cosmetics (↓5%)
- give her cosmetics (↓10%)
- ask her to clean the pool (↓10%)
- clean the pool (↓5%)
- tell her you’ve cleaned the pool (↓5%)
- doing yoga (↓10%) (only avalaible on Lisa girlfriend path)
- paying $350 for private punishment (↓30%)
- paying $700 for private punishment (↓40%)
- paying $1000 for private punishment (↓50%)
Alice:
- give her $15 (↓5%)
- give her $30 (↓10%)
- give her $70 (↓15%)
- give her $200 (↓25%)
- give her $350 (↓40%)
- throw the spider outside (↓5%)
- kill the spider (↓15%)
- watch TV with her (↓5%)
- successful leg massage (↓5%)
- successful leg massage using candy (↓10%)
Lisa:
- help her with homework with mistakes (↓5%)
help her with homework without mistakes (↓10%)
Kira:
- kissing lesson (↓10%)
- BJ after catch her using the sex machine (↓30%)
- HJ at the pool (↓10%)
( Thanks to the V0.9 walkthrough

)
Take care cause a lot of action increase eric's influence
Concerning Lisa, if I understood what you've written, you chose to be Olivia's boyfriend so It's to late and you probably made a HUGE mistake cause you won't see a lot of content. Sorry