Since there are some fields that exist and are used in GRID, that are not present in the CTP, we need to find a way of storing this data in CTP custom fields.
Since all the problematic fields are already identified, we can create a custom customer type "grid-customer" that contains all of these fields. Later when importing customers, we need to append all these fields as custom fields of the custom type "grid-customer".
This is how the structure for importing using a generic importer could look like:
{