I reread s1 ch 30 and 31 and I saw that Daiki was married to Ueyama Miu, so s2 ch30 would mean that Taichi and Miu are the actual siblings. This new ch would confirm so imo since Taichi didn’t like Daiki being the oyabun in the beginning. But in ch30 said Daiki was similar to Takeru (the dad), so I think that Daiki grew up with Miu and Taichi, then ended up married and having Toma with Miu. here's my new family tree: https://mangatoto.net/aok/xfs/attachs/5e1cc7855d331a0cdd42c5642b40d06ef318292c_2512_1256_259032.jpeg
I reread s1 ch 30 and 31 and I saw that Daiki was married to Ueyama Miu, so s2 ch30 would mean that Taichi and Miu are the actual siblings. This new ch would confirm so imo since Taichi didn’t like Daiki being the oyabun in the beginning. But in ch30 said Daiki was similar to Takeru (the dad), so I think that Daiki grew up with Miu and Taichi, then ended up married and having Toma with Miu.
here's my new family tree:
https://mangatoto.net/aok/xfs/attachs/5e1cc7855d331a0cdd42c5642b40d06ef318292c_2512_1256_259032.jpeg