How do I blend between pixel art sprite loops?

First time I've posted here, although the other guy working on the game I'm making posts here all the time. He's doing all the code stuff and I am doing animation - so I should say now if I get any answers here that involve lots of code, I personally probably won't understand what you are talking about, but he will, so it will still be appreciated.

Anyway. I am animating in pixel art using sprite sheets, and I have set up my animations in the animator so my character can change between (for example) standing and walking. The trouble is, I have animations where my character is doing additional things, lets say playing with a yoyo. The character can perform this action while standing and while walking. I want the player to be able to start playing with the yoyo while standing/walking and then switch to the other state without the entire current yoyo sequence finishing. So for instance if my standing yoyo loop was 8 frames, and my walking yoyo loop was 8 frames, if the player is standing playing with the yoyo and directs the character to walk on frame 4, I'd like to switch to the walking animation loop starting from frame 5.

This seems like the kind of thing blend trees might accomplish, but as I understand it they won't be much use to me using 2D pixel art sprites.

Anyone have any ideas how I might go about solving this?

Cheers