DesignMerge will prompt you to select a data file the first time DesignMerge wishes to apply one to a document's DDF. Additionally, if a data file has already been selected for a document's DDF, then by default DesignMerge will display a Verify Data File dialog each time the document's DDF will be using that data file. An example is shown below:

This dialog allows you to immediately identify the name of the data file that DesignMerge is about to process and provides several choices:

Select Data File: Click this button to choose a different data file for this merge session.

Cancel: Click this button to cancel the merge session.

Use Current Data File: Click this button to confirm the data file selection and continue with this merge session. 

Prompt for Data File Each Time: This preference determines whether DesignMerge prompts you to confirm which data file to use when processing data for any document.

• Select this check box if you would like DesignMerge to continue to display the Verify Data File dialog before processing data for a document.
• Deselect this check box if you prefer DesignMerge no longer prompt you to confirm which data file to use on a document. When this preference is deselected, DesignMerge will automatically use the data file that was previously selected for the current document's DDF without prompting you for confirmation.

You can change your Prompt for Data File Each Time preference at any time. This preference is available on the DesignMerge Preferences dialog (DesignMerge > Preferences). 

If DesignMerge is no longer prompting you to confirm which data file to use, but you would like a document's DDF to use a different data file, you can simply select the new data file. There are several ways to do this. First, open the document. Then, apply one of the following actions:

• Open the DesignMerge panel menu and choose Select Data File.
• Open the DesignMerge menu and choose Setup > Select Data File.
• Open the Data Source Definitions (DDF) dialog, confirm the Current DDF pop-up menu is displaying the DDF that you wish to edit, and then click the Select button (which is on the bottom right corner of the dialog).