Thought experiment that I'm looking at as we have a chance to reset a few question marks with the reboot.
The transition from the Yoritomo's Alliance to the Mantis clan was always controversial in the old game for a few reasons, but one of the big ones was that many of the Minor Clans that merged with the Mantis seemed to get lost in the whole Mantis pirates and mercenaries ascetic. It was quite jarring to see the traditionalist Centipede with their Lady Sun worship suddenly becoming the midriff barring Thunder shugenja of the mantis and the Fox merger and the transition to spirit animal masters was always seen as sort of odd.
But as I said with the reboot we have a chance to course correct some of those issues and maybe get a newer and clearer direction for the Mantis with the new setting.
For me that starts with which minor clans would be most suitable to make up the core of the new Mantis Great Clan and for that I think we need to scrap some of the old expectations and come in with a fresh perspective. Most clans have a four major families and each serves a role in the clan as 1 bushi, 1 courtier, 1 shugenja and 1 wildcard family. Assuming we want the reformed Great Clan to follow that ascetic then the Mantis are the obvious choice for our bushi family, however they also have the Tenkinja which is too interesting an idea to just throw out so I would propose that they could cover both those roles (similar to how the Bayushi are presented as both a courtier and bushi school but separate the two traditions like they did with the Seppun and Miya in Emerald Empire). Once we have that position established its now time to look at the other families that would make a good fit for the Clan.
While some may have balked at the apparent loss of identity the wasp were always presented as the most loyal of the Mantis subfamilies with Tsuruchi being the first to swear allegiance under the Mantis Banner when the great clan was established. And the Tsuruchi to me were always the most Mantis like in their refusal to subscribe to the traditional views of Bushido. Given that the RPG has already hinted that Tsuruchi has some sort of contact with the Mantis and his respect for Yoritomo I could see that crossing over to the new clan again. They could very easily become our wildcard family fulfilling the shinobi/scout role as their bounty hunter and archer style would be a good fit for that position in the new clan.
So now we are left with the question where do we look for our other families to join. This is where I see the real divergence happening as I think there are families that would in my opinion make a better fit to the clan than the old ones. For starters I would look at the Tortoise as the next most logical family to join as they share many of the smuggling traditions with the Mantis and their connection to the Imperial court being a pseudo Imperial vassal family tasked with monitoring gaijin trade and means that they would lend a certain air of authority to the clan and could become the basis for the clans courtier tradition or a second bushi/wildcard group.
And for our fourth family I would propose something completely off the wall and suggest that a splinter of the Yasuki family be merged with the Mantis to form a new Carp Clan that would become part of the Mantis. Now hear me out Crab before you start grabbing your pitchforks this would be a way to further recognize the shared heritage of our two clans and there is a logical reason for this. Part of the problem with the old game was that mantis holdings were scattered all over the place with the Yoritomo controlling the Islands of Silk and Spice to the south, the Wasp controlling their castle that straddles Scorpion and Lion lands in the center of the Empire along with the Kitsune lands and then in the North we had the Centipede lands. Made for a very disjointed looking territory claim so what I would suggest is that as part of the formation of the new Great clan they are ceded land on the mainland that comprises parts of the southern Crane territory and a bit of Crab land and those are awarded to the Yasuki based on old claims from their days as a Crane family (so sort of a reverse Daidoji Hachi claim) and the fact that the Crane are unable to support those territories in their post tsunami period. This would connect better to the Wasp lands (especially if you also include a little Scorpion land to spread the loss of land complaints around) and would only really leave the Tortoise partially outside of the complete realm of influence, however given that their primary territory is the surrounds of Otosan Uchi it is possible to hand wave that, especially if they set up a secondary trade hub south of the capital.
Thoughts from others on that suggested change.