Получил письмо от Михала Милевского.
Оказывается, не все так плохо:
Secondly, as you know, Anton got his Big Y results, and based on what I see in YFull, he shares one SNP downstream of FGC1155 with David Knize from Czechia (sample YF01517 in YFull), so they both form a novel subclade under FGC11555. This new SNP is 3024558 T>G (FGC11627). I think David Knize should be placed in a new category "R1a>Z280...>L1280>FGC11555>FGC11627*", while Anton and his two relatives from Russia/Belarus should be placed in category ""R1a>Z280...>L1280>FGC11555>FGC11627-A (one more Big Y needed)".