I currently have two grandfathered UNLIMITED data plans for my two phones (two separate lines). Data usage currently rarely exceeds one GB (averaging about 1/3 GB).

I've been wondering whether I could transfer one of my grandfathered unlimited data plans to a 4G tablet that would use much more data, both Wi-Fi and 4G. I'd then get the lowest tier data plan for the second phone line when I upgrade my wife's phone.

I know that predominently Wi-Fi usage and temporary tethering while away from hotspots would probably be the least expensive way to go, but if one of my unlimited data plans could be used, it would be an option.

Suggestions?