Walkthrough for the new part:
-after you get the Book of Sizan back, use it to receive a needle
-in your front yard take the pink bike seat under the bush on the left
-enter the shed in the backyard an take the wrench directly by the door on the left
-in the kitchen, talk to mom
-give her your dad's jeans
-talk to her again to get condom
-use needle on condom to receive useless condom
-enter your sister's room and talk to her
-use the seat on the bike to repair it (Joey uses the wrench automatically)
-give mushrooms to your sister (they are in the drawer next to Lucidas bed)
-take cellphone from drawer where your sister stood in her room
-use cellphone with the picture from your dad in the hallway
-use the phone and press '3' to print the picture
-go to your room and take the picture from your printer (under your desk)
-give picture to your sister
-give useless condom to your sister
Enjoy!
There are some more new items (the aforementioned pregnancy test, also a swimming suit which is found on the dummy in your sister's room (outfits change with each visit)), but I found no use for them yet.
Pls.