Different API settings for forms


I’m using the Mailchimp add-on.
The add on requires the API key and then on each form I can choose what list I want to use in my list.
What if I wanted to use a separate Mailchimp account for different forms?
How can I set the API key in the form settings?

I’m asking about Mailchimp but I would really like such a solution for all add-ons, Dropbox, Stripe etc…

I tried looking at the hooks but I didn’t find what I was looking for.

Thanks in advance for any help