Hi Patrick, thanks for using Relational Migrator!
Yes it should be possible to do what you are asking about, although the approach differs for embedded documents and embedded arrays.
To add structure to a mapping rule from a single table, you can rename the fields with a dotted path. For example you could change the name of the latitude field to deployment.location.latitude. You don’t need to create a separate Embedded Document mapping in this scenario.
To convert multiple fields into a single array, you can exclude the original fields and add a new calculated field (image_gallery) which returns an array result, i.e.:
new Array( columns["image_1"], columns["image_2"], columns["image_3"] )