The forms require the user to enter numbers and these are totalled in the final formfield  via an existing 'onkeyup' function.

I used keyup to copy the value typed and add it to the summary table. However in doing this, the existing 'onkeyup' function written into the form no longer works and so the total is no longer displayed. I tried using keypress instead (which still had the same issue), or including the function from the onkeyup in my keyup function, but it just didn't run. 

Any ideas on how to work around this? I can't modify the existing code.