LakeDogRealty

I am somewhat of a novice in Squarespace and am attempting to make substantial changes to my site. We are a realty company with two companies in our one office: Lake Dog Realty, LLC for lake properties and Realty Experts of Alabama, LLC for our off-lake properties. I need to be able to put both companies on one site for several reasons (our agents overlap between the companies; our homes overlap, etc.). The site was created with the URL www.lakedogrealty.com. I have other URLS, such as www.realtyexpertsal.com, directed to the homepage of www.lakedogrealty.com. I would like to have Lake Dog's logo on the left as it already is and add the Realty Experts of Alabama on the right. The logos look the same (colors, oval, size, etc.), except the dog mascot has a life preserver on the lake company and a business suit and tie for the realty experts one. Can someone please help?! I am willing to pay. I am also open to suggestions for other ways to do this. I considered two "landing" pages depending on the URL but then I think I still need the header to have both company logos with the naviation tabs all the same for all the pages. I am in the predicament of not knowing what I don't know. Plus, I don't know how the changes will affect viewing on mobile devices. Thank you!