Since there was a problem with a forum and some posts were lost I’ll post my tutorial for once again. 
I understand that the hard part here is that you have one mapping associated with two different keys. Here’s what I would do:
Firstly, create an Axis Mapping and associate the keys you want with it:
Then you can create that blueprint:
Now if you want to check if any of the corresponding keys are pressed you just have to check the value of IsInputPressed variable.
I hope this is what you wanted. 