Where I should put it? Main site or subdomain?

I currently manage a property (bnb) management business on mydomainname.com. The website is referred to the property owners. I have developed a new website for guests who will be able to book directly the properties of the bnb management business. The website of the property management business referring to the owners of the properties is already built and it is doing good so far. Here are my options:   I can either move the website from mydomainname.com to partners.mydomainname.com and host the booking website under mydomainname.com. Or I can keep running the bnb management under mydomainname.com and use booking.mydomainname.com for the new booking website. Although I think that it won`t make the website easy to share (long url). Share the property booking system under a different domain name. What`s your opinion on that?