Transferring ownership from one squarespace account to another with Circle membership

Hi there. I'm not entirely sure if this has been covered elsewhere so apologies in advance.

I have been doing some volunteer work for this amazing US foundation and have helped them with a few things including some minor edits to their existing website.

However, they are now ready for a full new version which I have been drafting. Too many design changes (whole revamp) to do them on the current site.

The thing is that their subscription is soon to expire and now they want me to take full control going forward. I hav my own account where I manage my own site and a few others for other people. But I am only a Contributor (with full Admin rights) in theirs. They no longer have contact with the current "Owner".

Now, I have just transferred ownership of the draft I was using (as they were the owners, although i is now expired), but I still need to:

Transfer their site/domain etc. to me. The hosting is with GoDaddy. They can keep ownership of that. I just need to be able to log into my normal Circle account and manage their webpage and upcoming store. But as the new owner. So that a) the original owner won't have access to the content I create and b) they may benefit from discounts I get as a Circle member?

Given their site is about to expire, and that I am doing a full revamp (starting from scratch), is it easier to simply finish creating on my draft and then just move the hosting to it once I'm done?

If so, anything I should be mindful of? I guess their subscribers I can just export and re-import on the new site. Anything else that may break?

Hi Paul. I think it mostly answers it. Though it would've been nice to keep analytics and other stuff, the site doesn't see enough traffic (yet) to warrant the hassle. The webstore is something that I will be setting up for them so nothing to be imported there. Just a few subscribers to the newsletter.

I think I'll go ahead and just finish creating their new website under my account and when done, change DNS settings in their domain provider an just let the last week on the other account expire a week later.

Thanks!