I would suggest:
- Stop Keiko and Yuno
- Ask Yuno to not speak until she is in the Nara compound .
- "She's your sister so it's fine to ask for help" speech to Keiko
- Point out that anything Yuno knows, it's probably known in Isan and it's good Goketsu(Nara's allies) found out instead of Hyuuga and nothing of real importance was said.
- Propose: The Nara adopt Yuno, then marry her in Goketsu:
- The secrets are protected by Clan secrecy laws, Yuno doesn't die, Leaf doesn't lose half of the remaining link to Isan.
- Explain that Goketsu will help Nara running damage control
- Optimize the Plan with the Clan.
Yuno probably marries Noburi(And is grateful we saved her).
The Nara find out that the Goketsu, when in front of a Nara secret, not only back down but start helping them running damage control ASAP, as true allies would.
The Nara finds out about Isan OPSEC in a controlled environment instead of Neji finding out.