NPC turning in animation needs the transformation matriz to update (forward and right vectors) without further rotation- please help

Hello dear colleagues.

We are making a 3rd person adventure using Blueprints (version 4.7.0 prevision). Our player gets close a NPC (a BP actor based, with a skeletal mesh as the root component) facing South with its associated animation instance blueprint. The dialogue is controlled via a collision box (another blueprint). The moment the player gets close to the NPC he reacts and turns 45 degrees to face our player (He now faces SW). OK! The turn is purely in animation (its pivot and transformation remains the same). Then we evoke a second animation and guess: The NPC returns automatically to its South facing attitude. NOT OK! We desperately need to update the transformation matrix of the NPC (45 degrees to the left) but without forcing a second rotation. All efforts we tried with nodes such as (Add actor Local Rotation, Set world Rotation… we tried all we could find) result in the same unwanted result: the NPC turns again. We need him to stay in the new animated pose but we need to update its transformation matrix “manually” without extra movement update. Is there a way to do this? Some kind of a function such “update actor’s forward and right vectors only” We tried to use root-motion in our 45 degree animation but the result is the same. We could have a “rotation in place” animation and play it at the same time we would rotate the actor but it would result in a very complicated via. Please help.
José Mateus