This tool enables one to merge multiple faces. Try out online FaceMerge tool here (broken). See the documentation for more information.
The server of the online tool above is broken. The tool use to run python routines to perform the merge. I have create a new version of the tool, which is full web (computations are done on the client's side).
Link to the new tool: https://pauldubois98.github.io/FaceMerge2/
Link to the new repository: https://github.com/pauldubois98/FaceMerge2