Bag switch
just drag the 10 slot to the slots of your old 8slots and it should replace and have your items be in that new 10slot you replaced it to. yes if you have something in a bag you cant unequip that bag, since the items would have nowhere to go, but you can replace bags fine
facepalm I had the inventory panel too far over on the screen, hiding the slots from view. Thanks for the help, man