To merge two or more targeted lists in Discover, you will first need to open one of the lists. Once in the list, select the contacts you want to add to another list. You can click on the tick box at the top to select all contacts on the page. You'll then have the option to select all contacts on the list.
Once the contacts have been selected, click on the ADD TO LIST(S) button.
To add the contacts to an existing list, in the pop-up window, you can scroll down to find the list or you can type in the name of the list in the selection window until you locate the one you need.
To add them to a new list, click on the CREATE LIST button.
This is a 2-step process. After selecting the list, click on UPDATE LISTS to add the contacts to the selected list.
Bear in mind that you can always send a distribution to multiple targeted lists, so there may be no need to actually merge the lists. At the time of distribution, Agility will deduplicate the contacts included in the release and will send the email just once to each unique email address.