Create blend space with animation montages

Hello, I was wondering if it was posible to create a blend space, but instead of using animation sections, use montages.
The thing is that I want to create a blended animation for Idle, Walking, and Running; with 2 different idle posses based on foot position the moment the character stops walking/running. I know how to make a montage for 2 idle poses and 2 walking animations, or 2 running animations; whatsoever, but then I don’t know how to blend it all together and set it to be driven by movement speed. Thank you for your time, any help would be appreciated.