GBP multiple domains

Client has existing “Google Business Profile” with many valuable five-star reviews associated with domain-name of original website.

The company has two divisions, so client had us create two new websites on WebFlow for each division. These have new domain names and unique content. The original website domain and content is now just a landing page or linking page for customers to link to either of the two new sites.

Is this the best structure? And, How to create a new GBP for the two new websites without disrupting the existing GBP and reviews?
Or other solution you advise. Thank You!

Here is my site Read-Only: LINK
(how to share your site Read-Only link)