Hi @Object_Story!

First of all, if you haven’t seen it - here’s our Help Center Article for Migrating to Klaviyo from Mailchimp:

• How to migrate from Mailchimp

Regarding the specific issues you highlighted:

1. For the “unsubscribed” issue, you may want to get in touch with Support, as the approach will depend on whether the users are supressed, or just unsubscribed from a specific list.
    
2. Did you create these sign-up forms in Mailchimp, or within Shopify?
   
   If you created them in Mailchimp, you won’t be able to redirect them, but you can choose one of these options instead:
   • Use the Klaviyo sign-up form builder to re-create your forms from scratch
   • Use a third-party list growth tool that integrates with Klaviyo
   • Integrate your custom form through your ecommerce platform
     
     If the sign-up form was created in Shopify, here’s a Community thread that explains some options in more detail:
3. While there isn’t currently a way to combine two lists into a larger list, you can combine two lists into a segment, by creating a new segment with the following logic:

   

I hope this helps, and thanks for using the Community!

- Brian