Mobile Wi-Fi

VivianR_2324759  I suggest that you have a read of the article : https://help.smarty.co.uk/en/articles/3417277-what-is-a-group-plan

You can add another sim to a group that you own and obtain a discount for each plan (not if they are on a special offer though). Alternatively you can start a new sim on a new account and add that to the group (slightly more flexible in what you can do with that method)