How to make multipoint calls with Skype?
While speaking to a person there is an option on top called Add to conversation will appear. Or you can simply click the +Add People button to select the people and make a group. This will gives you an easy way of conference call.
Hope it works :D
Sign in to Skype and press the (Create a Group) icon. After that, drag and drop the contacts you want to call in the provided field and click the green Call Group button. Check the official web page for further information. If you're using a Mac, check the Mac Support page.