Edo tensei was created by Tobirama Senju.But who was his test subject? I believe izuna was tobiramas subject. he felt bad about killing him and tried to bring him back for madara. since the senju and uchiha become konoha. tell me what you think.
Tobirama probably wanted to bring back his dead brothers
Since he died before the formation of konoha, his dna might be hard to come by, since we don't know when Tobirama invented edo tensei.
tobirama wanted to bring back his own brothers. not izuna