It appears that you can work with FreeMind mindmaps in MindMaple sotware, which will basically allow you to convert .mm files to .emm files with the program. Used to transfer brainstorming maps from one software to another. Perhaps possible in other similar programs.
Convert FreeMind mind map file to MindMaple mind map document.
We found 2 software records in the database related to .mm to .emm file format conversion.
Microsoft Windows software - convert mm to emm on Windows
A mind mapping and information organizing tool
Convert from mm file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned mm to emm. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert mm to emm on OS X
An app for project managing, concept mapping, brainstorming, etc.