Some blocks provide a star icon which can be used to change the functionality of the block:
For example, to add else if and else clauses, the user needs to click on the star icon, which opens a new window:
You can then drag else if and else clauses into the if block, as well as reorder and remove them. When finished, click on the star icon, which closes the window, as shown here:
Note that the shapes of the blocks allows any number of else if subblocks to be added but only up to one else block.