By your question I do not understand if you have problems sending values to the function or to collect values.
In doubt, I made an example using the 2 cases.
Create a function. Add one input parameter (Champion) and one output parameter (Champion Selected):
In the character blueprint, create two variables of type string (varText1 and varText2). When you click A, the variable (varText1) is set to a value that is entered into the function:
Within the function (see figure 1), the variable will be printed and with an append it will eventually be stored in the output parameter (Champion Selected) of the function.
The function ends by defining the value of the second variable.
Again in the character code, pressing C, variable 2 (varText2) will be called. If A or B have already been pressed, the text Champion + was selected will be written:
