composite multifield as a property for Single Line text datatype in content fragment model

Is it possible to customize the OOB content fragment model datatypes(single line text for example) to render composite multifield?

So that we can have more than 1 field inside multifield for content fragment authoring.

I followed this article from git but that's not the complete solution.

: https://github.com/AdobeDocs/experience-manager-64.en/blob/master/help/sites-developing/customizing-content-fragment-model-data-types.md

Any help would be appreciated.