The VLF merge tool works with merge lists which are lists of Framework objects. You can:
The merge tool has been primarily designed to assist multiple designers and multiple developers to concurrently develop a single master Framework. They do this by continually merging new or modified Framework objects back into a single master Framework.
You can start the merge tool when using a Framework as a designer like this:
The Merge Tool Window
Using the Merge Tool
Example of Combining Two RAMP Framework Definitions