いきなり本人に誰何するのも無粋と考えました。

tbd

I thought it would be boorish to challenge his identity without warning.

そのため、僕にとってのココは「遊び相手のお姉さん」で、家族のひとりとしての認識しかなく、親父に誰何するような存在ではなかった。

tbd

For that reason Coco was, to me, 'an older sister I can play with' and I thought of her only as one member of the family not as someone I should question my father concerning her identity.