If you fill in the dates where you have availability, then possibly another owner can share a guest with you. For example if I have an enquiry for a 2 week holiday and I have one week available, I could see on the calendar if another apartment was available and possibly arrange a booking for one week at my apartment and another week at your apartment.
To fill in your available dates:
Click on + Google Calendar
Enter Username: corcovadaowner1
Enter password: albufeira2008
The calendar is easy enough to use -- if you add some contact details in the title, it will be easy to get in touch with you.