Other fixtures outside of your usual schedule can be created via "Other fixtures"
Please go to Fixtures > Other Fixtures.
To input a custom name for your group of fixtures e.g. "League Play-off match" please go to "Maintain Groups"
From this page you can create a custom name for your group of fixtures and how you wish the fixtures to be displayed:
You can then create the fixture - please ensure you select the relevant "Group" you have setup (you can also list fixtures just under "Other fixtures"). If your teams are already within your league, you will be able to select them from the drop down menu's. If they are external, please click "Maintain teams" > External > Create New" whereby you can create teams.