@Lanfear tldr they got setup and need to put her in power to clear their names.
When Ryoma and co where traveling through the region, the guild master of the area pretty much forced Ryoma and co to under take an emergency quest. If they didn’t the guild master could revoke them of their license and they would lose their means of income.
The quest turned out to be a trap setup by the nobles, they needed a decoy while they transported the illegitimate 2nd child into the kingdom. Since one of the 2 twins has silver long hair, the same said of the 2nd child they used Ryoma’s group and fed false info to the Knights group to attack the caravan.
After Ryoma and co survived they managed to figure out what happened but now they are in the situation where they need to clear their name. They cant go back to the guild because the “employer” died in the attack and the guild master can prosecute them out for failing. They cant go to the other guild masters because who are they gonna believe. A group of low ranked adventures or another guild master.
So Ryoma purposed to Lupis that if he can help her win the war and put her in power she will vouch for Ryoma and co and help clear them.
Edit: changed Meltina to Lupis.