We'd like a confirmation from Vercel staff before we make a domain change, so we're asking here first.

Setup today

• We own scanlonsellshomes.com. It's registered at Squarespace, and Squarespace hosts the DNS. We are not changing nameservers.
• reviews.scanlonsellshomes.com is a CNAME to cname.vercel-dns.com. It's served by a third-party vendor from a project in their Vercel account (a multi-tenant platform). We don't have access to that account.
• Our site is the scanlonsells-site project in our own team, which is currently on the Hobby plan. Today the project only has scanlonsellshomes.blog and www.scanlonsellshomes.blog.
• There is currently no _vercel TXT record on scanlonsellshomes.com.

What we plan to do (not yet)

1. Project → Settings → Domains → Add scanlonsellshomes.com and www.scanlonsellshomes.com.
2. If prompted, complete the project-level "verify access" step by adding the _vercel TXT record.
3. Later, change only the apex A record and the www CNAME at Squarespace to the values shown in our project.

What we will not do

• Add reviews.scanlonsellshomes.com or *.scanlonsellshomes.com to our project
• Use Connect External, Verify & Claim, Move, or Transfer
• Switch to Vercel nameservers
• Touch the existing reviews CNAME

Questions

1. In this situation, will adding the apex and www at the project level require the _vercel TXT verification?
2. If we complete project-level verification, could it detach, reassign, disrupt, or trigger re-verification of the other account's existing reviews.scanlonsellshomes.com project domain?
3. Does project-level verification change account-level ownership of scanlonsellshomes.com in either team? The docs say it "will not move the domain into your account." We'd like to confirm nothing changes on the other team's side either.
4. Will SSL issuance and renewal for reviews.scanlonsellshomes.com keep working unaffected?
5. Is there any point in the project-level flow where the default path leads to a claim or transfer, so we know what to avoid?
6. Does our team being on the Hobby plan change any of the answers above?

Docs we've read: Adding & Configuring a Custom Domain (Verify domain access), Troubleshooting domains (Domain ownership errors), Claiming Domain Ownership, and the KB article "Domain Linked to Another Account." None of them covers the effect on another team's existing subdomain, and that's the gap we're asking about.

Thanks in advance.