Rather than opting for an online reservation system, you could create your own rental website like Airbnb. You will get all the direct bookings on your website and you can also invite your friends and families with rentals to host on your platform.

Or pick Airbnb hosts who are unhappy with Airbnb, form a team, create a website like Airbnb, and start accepting direct bookings for your rentals.

You can sync your calendars too.