Yes, lets say i have my collection type “Articles” and i want to give the possibility to the user to generate some geoData (optionally) related with an article, so at the time of creating an article the idea is to bring up a step wizard, asking, do you want to add geoData? yes/no, if yes the next step is to add country and postal code, and the next step will create the article and geoData in its corresponding collection. If answer is no, will create only the article.
country and postal code, are information only used to generate de geoData, but there is no need to store it in any collection.