Adding all opt-in in one list

Adding all opt-in in one list

Hi,
I followed this thread to set up my test opt in campaign https://help.zoho.com/portal/en/community/topic/setting-up-optin-campaign it was successful for the test list and i have now there the dedicated segment. In a meanwhile I have some other lists where I am going to segment the contacts for opted in and not opted in. 
I have also a third list - migrated subscribers from another marketing automation system. The question is how can i create 1 master list which will contain:
1) only those who opted-in from another lists
2) Imported subscribers from another marketing system (they are in the separate list)

Thank you!

Katya