...
Download the most recent mergemodels tool here 
MergeModels Tool
Change the input file (mergemodels.inp) to reflect the structure of the two configuration directories of the models to be merged. In this file, the first line must be the location of the configuration files of the first model to merge (referencing the Config folder). The second line in
this file is the location of the configuration files of the model you want to add to the first model (referencing the Config folder).
...