This script allows you to make certain players share their inventory.This can be from 2 to an infinite amount of players.Different groups can have a different shared inventory as well.
Select version for changelog:
Changelog
The item is now a 16x16 texture, so even low end devices can handle it well.
Add yourself first then player 2
Put it the same number ( i prefer 1)
If it still doesn't work then watch the tutorial :D
hope this helped