Cart Support is a mod that changes the way you control your cart in-game. 

You can set the maximum distance to allow support from other players, the maximum number of players, and the amount of weight that will be reduced per supporting player. You can also turn off the option to include the puller as a supporter.

You will need to download this mod and install it first before you can use it. To install it, you will need to download BepInEx, which is a free, open-source game. You will also need to download the Cart Support mod from the Nexus Mod Manager.