^^^debatable, last I checked gave the impression Miko grew up as sort of the family pet of the Raiden twins or smth (and IIRC has at least once described herself as Ei's "familiar" whatever that now means). In any case her and Ei certainly don't talk to each other in a mother-daughter sort of way.
OTOH Ei very concretely created both Edgy Pinocchio and the Shogun Terminator and is thus the closest applicable analog of "mother" to both so... yeah. (Which also makes her relationship with the latter even weirder but eh.)