https://i.gyazo.com/097063f746af5fa401ef7b80d50c85cc.png

1) Download WBT FMM and a modpack
2) Open WBT FMM and click Select Modpack
3) Select the modpack you downloaded that is WBT FMM Compatible.
4) Click Imported Selected Modpack
5) Play Factorio c:

SImple And Easy To Use!!!

Download:
https ...

I say instead of placing the belts on the underground belt just be able to place a belt on one side of the underground and it automatically replaces the full length with the belt. Some QOL researches like Inventory Size, Crafting Speed In Inventory, Etc...