Redesign of the main frame + find solution to connect encoder properly

[Klipton1]

When ordering motors for this project, i.e., 2x GBM5108-120T you find out that the hole pattern is different and that there is now a hollow shaft. How would one change the mechanical design to connect the encoders?

I made an error in the mechanical design as I was currently putting a clamping force on the hollow shaft. This in turn lead to motor problems running not smooth anymore. Any help, tips or tricks would be greatly appreciated!