it would make sense at a "dna level" if and only if their dna actually fused with hashi dna, and by fuse i mean in a process similar to how peoples genes being created from each of their parents cells passing certain genes, since that more than likely isn't the case it makes sense to say they just have a transplant that "coexists" with the rest of their body, it would still be a part of their body but their uchiha dna never would have fused with hashi's dna, and the hashi cells at some point would at some point more than likely get replaced by newer celss since cells die, and if their body was majority uchiha cells then it would make since that at some point they would be overrun, or remain at pratically the same percentage, also it makes zero difference to worry over the simantics of defining anyone in nv w/transplants as x% this x% that, naruto is a story with its own rules and if a character gets certain powers because of any reason, that should not change what the call themselves.
tldr, dna most likely didn't become one set from the two, transplant dna would most likely get overrun by their own dna, it pointless to worry about it
