Reclaiming Site Ownership

Site URL: https://www.tamarackvalleyfarms.com

A current client previously had a site through Squarespace. The domain (above) is owned by the previous designer (I assume also through Squarespace). Is there any way to request ownership of the domain through Squarespace? The WHOIS registrant is not replying. Could Squarespace contact the owner on my behalf, to keep them anonymous? Has anyone else run into this problem? 
 

The domain could be changed, but it’s already on all the client’s existing packaging. 

I am having the same problem, did you find any way to contact the domain owner?