How to change a AI characters animation at any time into a new animation smoothly.

Hello and thanks for reading,

I am using solely blueprints. UE 4.23

I have an AI Character using a Behaviour Tree and BlackBoard, also this character has an ‘Animation Blueprint’ with the animation state machine logic, this is updated when the behaviour tree logic has been.

I have longer animations 8-30 seconds that the character uses and triggers (such as perceptions) that change the state of the AI character.

My question is, how do I change animation at any given time, ie. the logic is updated from a trigger, to smoothly transition the character to their new animation at any time?
Is this even possible!! I hope!

I can change animation but just not smoothly.

Note *
If montage is the solution, my character has different branches(and animations to suit) depending on the trigger type, so as long as that can be worked into it I can change to make it work.

I have spent a lot of hours looking over all options and documentation so any help is very grateful.