How to blend two different animations for the same action

I have two run sprites for running. One is when the player is running and the other is when the player is running and shooting at the same time. When I was looking at blend tree tutorials, it looks like speed or axis are used to determine how to blend the two but the difference in which animations I am using is if the player presses the fire button or not.

You could add a third variable to your blend tree. A boolean “isShooting” would be fine in your example.
The boolean then allows to choose which animation to play.

That’s what I was trying to do but the only params that I can pick from the drop down for the animations are params of type float. None of my bool variables show up.

Indeed I was incorrect, blend trees only allow float parameters as they are directly related to directions.

You could, however, add a second state “ShootingWhileRunning” in which you put your blend tree that you construct similarly to the one you have already, except with the “ShootingWhileRunning” animation.

Then, in your base layer, you create a bool that allows to select between the 2 states.