Hello,
The multi-list subscription feature can be implemented without an issue. Please note that I was unable to access the site listed in the description due to a 404 Forbidden error, so I was unable to see if any customizations were present in the form that would affect the pricing or timeline.
In regards to the resubscription, each ESP has their own policies. Some platforms allow simple user re-sub, while others require the user to reach out to support from the email address in question and request resub. That functionality is completely based on the platform's handling of potential abuse.
As a certified email marketer with over 15 years of experience, I specialize in running email marketing campaigns from end to end, including planning, creative development, scheduling, trafficking assets, segmentation, testing, and analysis.
At the very least I would like to start the conversation to get an idea of the exact scope and help you get your form operating as intended right away. Thanks for your time.
Best,
Anthony