Since you only want 1 result to matter of the two inputs (ring and string), you could consider a compare function that checks the string box, and as long as it is not empty [""] (meaning data has been entered), then disable (with property node) the ring elements so no output (or a known output...0) from the ring will occur. You'll then need another function to reset all that later on. I'll admit though, this is not the greatest approach, but one to look at.