Hello all.

Here is how it goes: We have Sansa Stark(CS) with the poisoned wine attachment(CS) on her. She is knelt and with the Snowed under(CS) plot card i choose her as the character to be put back into my hand.

Here comes the question, does the poisoned wine attachment go to my opponent's discard pile, or can he choose to kneel one influence after i take Sansa Stark at my hand and move it to another character?

Poisoned Wine, as an Any Phase: ability requires a standard player action, and thus cannot be triggered in time. Both Sansa and any attachment on her become moribund in step 3 and 4, respectively, and move to their respective destinations (hand, discard pile) in step 6, which ends the framework action window. Only after this opens a player action window in which standard player actions (such as triggering Poisoned Wine's ability) can happen, but the attachment has already left play at this point.

If you have no clue what the steps are, have a look at the FAQ, specifically the details of the timing structure.

Kelemvor said:

When a character leaves play, all of its attachments are discarded as part of the effect that makes it leave play. That effect must resolve completely before you can play any other "Phase" effect.

So once it initiates, Snowed Under must resolve completely, including removing Sansa and discarding any attachments on her, before any player can trigger an "Any Phase" effect like Poison Wine.

In general, if the character leaves play out from under Poison Wine, the attachment will be discarded unless it is specifically saved.