Sima Ling is available for recruitment after completing Shangguangs personal quest to learn the Baidi whirling blade, though you still need to bribe her with enough gifts.
Ye Fei is available for recruitment at Lotus Lake after carries off the body of that one guy from Leng Wuqings quest involving the pirates. There will be a fight against some pretty strong guys but you can lose and still recruit him.
Leng Wuqing well as far as i can tell after you help him with the pirates at Mount Lian’gu he goes somewhere else implying to you that you can recruit him. He appears at Peach Blossom Forest after the events on the North with the Tianlong Gang and the Sects Alliance. Just talk to him and there’ll be some quests to finish and you’ll be able to invite him after. I assume you have to finish the questline with the pirates and all before the whole confront in the North for this to be true. His cultivation method is crazy good with Hidden Weapons.
Shangguan Hong – She will come after you beat the really, really hard toad guy for that one quest to get toad skins in Murkwood Forest for the shady merchant with two bouncers next to him in Pingkang City. Afterwards you can see her in the middle of Pingkang City just standing there. Raise her affinity to 40 and she’ll offer a quest at Qingmu Sect (but you cannot raise her affinity past 40 yet).
Lu Xian’er – Note in her personal quest later if you cant find the old lady she’s at Skylinemont or mount autumnscale i dont remember which one. I say this because the game doesnt tell you or i think even give you a quest telling you to find her. This is an example of something that happens several times during the game where a quest isnt give and it’s just up to you to have paid attention to the dialogue and chose to follow up on it without prompting. Also i recommend doing the sidequests you unlock at Pingyang from doing Lu Xian’ers personal quest to go there involving the man and his son before doing the quest at Sweetspring mentioned to you at Wudang.
Bai Jin – Meet him in Luo Village after the 1st completion of Mount Wanzai, he’ll give you a quest to go back to Mt Wanzai. Then meet him back in Luo Village and he’ll give you a quest for PetalsFall Forest. After the quest in PetalsFall forest I was able to raise his affinity to 60 and recruit him there, before his next quest.
Wei Huo is just follow the game tutorial on recruitment.
Chen Lenxi – If you do his personal quest i guess you have to let him get taken in by the detective during it instead of deciding to believe in him or else you will eventually end up losing him forever which happened to me.
Huo Changqing becomes available for recruitment some time i dont remember but she shows up at i believe Fengcheng at some point in the inn, just help her out and dont lose the fights and you can recruit her, may have to give gifts i dont remember.
Di Zui i never figured out despite him showing up in several quests.
Redhead guy in Yanfu town, cant remember when his sidequest pops up but just help him and always takes his side and you can recruit him afterwards in Tancheng.
Li Yuanxing is available for recruitment after its mentioned to you that the beggars sect is having troubles involving that stage they have at the front of the city. Don’t remember when this is mentioned to you just that it is. To recruit him you have to find out the truth about what is going on instead of just going to sleep at beggars sect to wait for the battle. Then after you find out you have to side with him then maybe lose during the fight in beggars sect, idk if you have to actually do this but it is mentioned as part of the plan, then win the battle against the two actual troublemakers. Then you can recruit him.
Yan Weihuan is available after helping Li Yuanxing. You have to goto Solitary Cloud Marsh, on the jungle area side, but you have a huge fight against some pretty tough people you have to win. Then after that you need to goto Bramble shade forest and search a side path on the right where you’ll meet him again. Follow up with him and puppet lady and he’ll join you automatically.
Puppet Lady I guess is available for recruitment after getting Yan Weihuan but I couldn’t find her again so I have no idea.
Frosty Condor is available by doing the quest to stop the bandits in Sweetspring. The Sweetspring quest involves some difficult fights which is why it warns you about starting it. After the bandits are dealt with go back to Eagles sorrow to see Condor school to unlock her.