"I have been very assiduously preparing excuses. A couple of them involve murdering particularly loathsome retainers and hiding the bodies before we see Uncle. A different bunch involve me acquiring a handful of injuries for plausible deniability but I figured you would probably veto those." 

Yeah no shit. 

"D-do we, need our own excuses, Da-jie?"

"No. A-Ying will share the excuses she decides on and we'll all coordinate around them."

Hmmm. All three of them are together, which makes plan: ask Wen Ying by herself somewhat more difficult. And if he tries to get her alone to ask her without her siblings around on purpose, she might figure it out and get suspicious of why. 

Oh well. He approaches the three of them. "Wen-guniang. Wen-er-guniang. Wen-gongxi." 

She rises quickly. "Sect Leader Lan. You just missed Sect Leader Nie, if you are looking for him."

"Not in this particular instance. I was...wondering if it would be useful to your cover if you accompanied Lan Zhan as she seeks out the remaining Yin Iron shards." 

Wen Ying leaps to her feet. "Would it! Oh man, that sounds awesome--can we, Jie? Please?"

"Sect Leader Lan, you aren't concerned that we would pose a threat?" She hadn't thought Lan Xichen trusted them that much, but she can't think of what the trap might be, here.

"I have advised my sister not to let you carry the Yin Iron, and to keep an eye on you. But honestly, at this point, if the three of you are pulling a long con, it is a very good one. And Wen Ruohan is not known for his subtlety." 

“Well then, it would be very useful to our cover. We would like to assist Lan-guniang as well. Have you found out where any more shards are located, Sect Leader Lan?”

"Not for certain, although we have a general idea of area." 

“Alright. How soon does Lan-guniang expect to depart?”

"Tomorrow morning." 

“We will be packed. Thank you, Sect Leader Lan. Is there anything else?”

Headshake. "Thank you," he says, and leaves. 

He informs A-Zhan that Wen Ying's siblings will be coming along after all and then goes to do sect leader things in his office. 

That evening Wen Chao shows up to be an absolute creep, deliberately wiping his muddy boots on Lan Xichen's floor, and making various ominous threats if the Lan Sect doesn't turn over their piece of Yin Iron. It's very upsetting but while Xichen doesn't have his little sister's omnipresent poker face he can do a good one when he needs to. 

On the plus side, nothing he says indicates that he knows any of the MANY things Wen Ying would probably have told him if she was untrustworthy, and while Wen Ying is plausibly smart enough to be a good actor, Wen Chao is not. 

Wen Ying has to get up in the middle of the night and go outside when she senses something wrong so that Wen Chao will only be a creep at her and not her siblings. He questions her loyalty; she questions his intelligence and threatens to blame him for the failure of the whole operation if he blows her cover. He departs. 

She doesn't sleep well for the remainder of the night. 

Lan Zhan knocks on the Wens’ guesthouse door in early Lan fashion the next morning.

Wen Ying answers the door fully dressed but ever-so-slightly disheveled, yawning and rubbing her eyes. 

"G'morning Lan Zhan." 

(Oh no her disheveled hair is cute oh no Oh No panic)

"Are you ready?"

"Yep. A-NING! QING-JIE! LAN ZHAN'S HERE!" 

"We're right here A-Ying, you don't need to shout!" calls a voice from the next room.

Wen Qing and Wen Ning appear in the doorway behind her, both more neatly presented. "Lan-guniang, good morning. We are ready."

Nod.

She waits for them to step out of the guest house before turning and leading the way through Cloud Recesses to its gates.

And when they pass through the gates Wen Ying grins and rolls her shoulders and does a cartwheel and yells whatever the ancient Chinese equivalent of "OLLY-OLLY-ENFREE!" is. 

"No more rules," she says, bouncing on her toes and grinning at Lan Zhan. "I tell you, it's a lot less obnoxious to have to obey way too many rules than to have to step lightly around Wen Ruohan's idiot ego but it was still starting to chafe." 

"Remain decent."