Vertical transparency effect on word by word animation

Hello everyone,

With the help of some online tutorials I managed to animate a text word by word in Fusion, not too difficult.

But my intention is to make the words change from transparent to solid as they appear, one after the other.
The only way I could find is to animate the opacity on the tab "Shading" of the modifier (for exemple value 0 at start, then value 1 after 25 frames because my text is quite short).

But that is not exactly what I want to get!

My aim is that the opacity should increase and move verticaly from the top of the letters to the bottom of the letters, and not horizontaly from left to right like in what I was able to do as I just described above, let's say over 4 frames of time per word. And only when the word is solid, the next one would start appearing (the text would remain of the same size, position, font etc. Beside its transparency, nothing else should change).

Could someone explain me how to proceed?
That would be great!!

Thanks a lot in advance for your hints.
Noukita