Add fixtures to preset

You have a few options here:

First you can merge new data into the preset by changing the paramiters you want to merge into the preset then storing onto the original preset and choosing Merge from the options.

Another two other options are Edit or Update

Use the Update button or keyword, In order for this to work you may need change the UpdateMode from Original Content Only to Add New Content, if the data does not already exist in the preset. Then choose the preset you want to update.

You can also use the Edit Button or Keyword, For example Edit Preset 2.1 to edit the first Position Preset will turn a number of the window borders green. You can then make any changes, like adding new data and press Update and choose the to commit the changes, if you want to abort hit the escape key.