I can now answer my own query. Here are the steps to take: -
1. Incorporate WordMerge.db into your database programming with a Command Button or other means of actuating it to create a text file with LE name headers for insertion into a LibreOffice Writer (.odt) document. WordMerge gives you the option to choose to send information from many retrieved forms (All) or just the open form (One) when you call it.
4. In LibreOffice Writer, create the document that will contain the Header elements placed where you want the layout Name contents to appear.
5. When you come to the place where you want the first layout element content to appear, select Tools, Options. LibreOffice Base, Databases.  Click New and select MyDatafile.txt. Select Plain Text as type.
6. You will be invited to name the field separator symbol, whether or not text is enclosed in double quotes, the decimal separator symbol and the thousands separator symbol.
7. You can also give a Name to your data source other than the actual file name.
8. Click Apply and save to return to your merge document.
9 On the Standard Toolbar in Writer, find the Insert Field command. It hides between the Insert Break and Insert Special Character buttons. Click on it and select More Fields from the drop down list.  highlight your new database and then highlight Mail Merge fields
10. From the list that appears, highlight your new database name, then highlight and click on Mail Merge fields, click on the + symbol in the right hand pane and select the fild you need for the drop down list that appears. The Insert command button will be highlighted and when you click that, the Header name of the selected LE contents is inserted into your documentat the cursor position . Repeat as necessary
11. When you save your working merge document, MyDatfile.txt will be saved as its data source.
12. To use it, click on the Command button or other device you have used in your programming, and choose the working document from the drop down list you will see in Sesame2.

There may be surprises in store for other versions than LibreOffice 6.4.

John