Select multiple segment points at once, then convert them to curve points. ( ver MD6.5 )
Main Menu → 2D Pattern → Edit → Edit Pattern (Z)
2D Toolbar → Edit Pattern Tool
Find and click the menu indicated in Location.
Hold down the Shift-key to select the multiple segment points that will be converted to curve points.
Right-click on one of the points and select Convert to Curve Point from the pop-up menu.
→ The selected segment points will convert to curve points.