If my eagles of the misty mountains have other eagles attached to them does the shadow effect on Whip Lash discards them ? I Thought it wouldn't because I don't think I "control" them…but I'm not so sure…anyone knows the answer ?…

Yes, you control facedown attachments on EotMM. Any cards that interact with "attachments you control" (Black Uruks, Wind-whipped Rain, etc.) can interact with those facedown cards.

Ok, Thanks ! It is really an awful shadow effect then…one of the worst indeed…