#whereas in the show you explicitly see him tell his dad that yanli

[winepresswrath]

Could you elaborate on what the yanli-jc wwx conspiracy is?

They are just generally in cahoots re: making sure he's safe and bringing him home, sometimes in defiance of their parents or society or just the likely fact of his death. The first time Wei Wuxian runs away Jiang Cheng wants to follow him because he's worried he'll get hurt. Jiang Fengmian says no, and when Jiang Cheng sneaks out in defiance of his father's wishes with his little rucksack in hand, Yanli is waiting at the gates to support him and tell him to bring Wei Wuxian home safe, implicitly siding with him against their dad in the matter of whether Wei Wuxian might be in real trouble and if so, whether Jiang Cheng's help might be valuable.

The second time is during the sunshot campaign while Wei Wuxian is missing- she comes in when he's brooding over Wei Wuxian's sword and tells him how grown up he is, fusses over him a bit and asks him to bring him back. Jiang Cheng fervently agrees, and looks actively relieved and pleased she's asking this of him- it's blatantly obvious he was going to do it anyway, but her support and faith mean a lot to him which I think is significant because he's usually so worried about failure and he knows Wei Wuxian has been thrown in the burial mounds and is almost certainly dead, but he's not actually frightened he'll fail her, he's just glad they're on the same page. He gets extra support this round because Lan Wangji is also refusing to believe Wei Wuxian is dead and taking joint missions to Yiling with Jiang Cheng and his own turn at sword brooding.

Breaking the pattern, in CQL she was originally going to go with him to talk to Wei Wuxian after he takes the Wens to the burial mounds but he kind of sneaks off without her when he sees her with Zixuan and then doesn't manage to bring Wei Wuxian home to her; she has a sad prophetic dream about it. The conspiracy is broken!

Until! They conspire to bring Yanli to Yiling so Wei Wuxian can see her wedding clothes. I personally think it's implied by the response to Zixuan's request for Wei Wuxian to be allowed at Jin Ling's hundred days ceremony that they were in on that together- either way they're both playing their part, because everyone from the Lan to the JIn know Jiang Cheng would happily take Wei Wuxian back and Yanli misses him. Whether they planned it or just moped really obviously is debatable buy money is on them being in on it together with Zixuan and maybe even Lan Wangji.

And then of course there's Nightless City, where Jiang Cheng notably does not try to get to Wei Wuxian but Yanli does, and then he finds him and loses him all over again so he can have a much more prolonged and less emotionally supportive round of refusing to believe Wei Wuxian is dead.

Bonus Round: The only time Yanli sends Wei Wuxian after Jiang Cheng it's when he's been captured by the Wen because he was already on top of the send Wei Wuxian home safe to Jiejie agenda.