It is not. I've done that with Visual Basic and Visual Basic for Applications (MS Access), but this is not directly possible in FileMaker. Best you can do unless there is a plug in out there that offers better is to export the data to a merge file and then import the merge data in to Word.
can you please share as how you did it in Visual Basic ? I did find some methods (link below) but not sure if they work good for bigger file (i have 120 fields and it takes for ever)
That would not be a discussion germaine to this forum as I was using Visual Basic, not FileMaker. It's been years, but Visual Basic is an OOP (object oriented Program). In Visual Basic, you can declare a Microsoft word "object" and then use "methods" associated with that object to create a document and "write" data from the Visual Basic program (This was the front end of an Oracle database) to the word document in a fashion similar to making menu choices and typical user edits directly in the program.
It's been too long for me to go into any more detail than that. Not only is my memory not that good but the software you'd use has undergone a lot of revisions since then.