Aww, we all knew what you meant by SERPS. It makes them sound like something very important, and well, they are. ;)In the short-term, sure, the DA of your existing site has the potential to give any pages you add to it a little boost in terms of authority, provided that the pages are easy to find (i.e., they are crawlable, not too deep in your site architecture, are linked to from important pages on the site, etc.).
Now, back to your question. In the short-term, sure, the DA of your existing site has the potential to give any pages you add to it a little boost in terms of authority, provided that the pages are easy to find (i.e., they are crawlable, not too deep in your site architecture, are linked to from important pages on the site, etc.).
BUT in the long-term, I can't really say if taking this route has the potential to harm your whole site -- as we still need more information about how you are structuring your business(es) for these two categories of cleaning services, if the new one will have its own branding or not, and how the markets for each one compare beyond both being consumer markets (including service areas -- are those different, overlapping, or the same)?
In the meantime, I'm going to grab one of my colleagues who specializes in Local SEO to see if she can you can give you any insight into how the path you go down may affect your performance in local search results. 