Identity patch is the original one which may or may not have been released by the dev. (Dev is on Patreon so let's pretend to assume its not). It's a very barebones ipatch that changes a few mentions of best friends daughter to whatever your chosen relation is and changes a few other dialogue lines based on the chosen relation. But the girls often call you by your first name and there are still various dialogue lines that don't fit a biological connection especially with Cory. Also some immersion breaking bugs where shit was poorly coded so the wrong dialogue/scene occurs despite relationship choice.
The improvement mod (which includes a modified version of the patch so don't need to download both) rectifies those issues and does a bunch of other stuff that I'm not going to re-list here. Just read the feature list on the mod post
https://f95zone.to/threads/goodnigh...dings-dirty-secret-studio.84531/post-14050656
So the main thing for the harem ending is that in Chapter 8 when everyone is discussing their feelings you have to have at least 24 Trust for Cory, and 21 Trust for Clover. Then you can answer "I love you both" and they will be open to an open relationship.
To get the added characters endings for the harem:
Jenny:
Chapter 15 she can not catch you having sex with either of the girls. So either have a stealth greater than 3 or don't fool around with them during the last night of the chapter. If you hear rustling at the door then you've screwed it up... Then answer "sure" when she asks for a second chance.
Tracy:
Accept the shower BJ in Chapter 8. Invite her to go on the trip and make sure to do all of her scenes including on the trip.
Nadezhda:
Just fuck her at every opportunity (you don't have to call her about the trip though if you want Tracy) and DO NOT make a joke about fucking your daughter in 18 years after she tells you she is pregnant.
Amara:
Just do her scenes and have sex every time you are given the option.