I'm not 100% clear on what you are asking, but I believe you're trying to overwrite a locally stored filemaker database on FMGO with a snapshot link file, which will not work.
A snapshot link is an XML file that stores "state" data of a referenced filemaker file (what layout you are on, what records you are looking at, etc..). It is not, in itself, a filemaker file, only a shortcut.
If you are hosting the database on filemaker server and accessing it via FMGO, then you would be able to do this by deleting the old snapshot link before distributing the new link.
There is no way in FMGO that I know of to "overwrite' an existing file. FMGO will automatically rename any same-named file when you add it to the FMGO documents folder.
Here's a bit more detail about FMGO and snapshot links:
SnapShot Links in FileMaker Go
FileMaker Go has full support for creating and opening Snapshot Links. Snapshot Links created in FileMaker Pro are readable using FileMaker Go and vice versa. The Snapshot Link feature is available to FileMaker Go users through the user interface as well as through scripting.
Snapshot Links are identified by a FMPSL file extension. FileMaker Go registers itself as the default handler of FMPSL files which allows Snapshot Link files to be pulled into FileMaker Go from external sources like e-mail, the Internet, or DropBox. The FMPSL file needs to be in the FileMaker Go "Documents" area in order to open the link. FMPSL files received from external sources are automatically copied into FileMaker Go. Once the FMPSL file is inside FileMaker Go, opening the FMPSL file works like opening any other FileMaker file.
Since Snapshot Links have many user interface commonalities with export, Snapshot Link and export has the same save / send options and a consistent interface similar to that of export.
The alert dialog for Snapshot Link allows you to specify the name of the Snapshot Link and also specify whether the current found set or only the current record should be included.
Thanks for the reply. What I'm looking to do is to easily move found records and or layouts from a filemaker 12 file to filemaker Go.
I've been very frustrated with the ability to interact with my mobile devies using scripts, so I thought a Snapshot Link might be a quick and dirty way to do this. I'm not familiar with xml, but since since a snapshot link is an xml file can't I import an xml file into my filemaker go file?