I assume they had proper guardian for a while until Oni-chan coming of age, like some distance family member, grand parent, etc. or the neighbour that close to them. they able to hold funeral after all, so someone surely handle or help them.
this is always a problem in translation scene. tho in...
it would not be consistent then.
number might be confusing for reader but but code name are almost default in military setting. and its been on their training, so its already in their vocabulary. changing it would break the setting.
but yeah, when they called "one" its really easy to confuse...
good job creating another hurdle.
tho yeah, its really not fair for Taeso if Mia just ignore his effort like that, but at the same time its also his choice.
and its nice to see Sunbae info dumping her like that, at least the misunderstood route are now gone.
she acknowledge that 001 leadership are the best, and she probably has quite high regard for him too, which make her feel so betrayed when 001 "abandon" them.