Reaching to you all as I am in the learning process and integration of Apollo and graphQL into one of my projects. So far it goes ok but now I am trying to have some mutatio
Yes, you can:
The fields on an input object type can themselves refer to input object types, but you can't mix input and output types in your schema. Input object types also can't have arguments on their fields.
Input types are meant to be defined in addition to normal types. Usually they'll have some differences, eg input won't have an id or createdAt field.