Short answer: no.

Long answer: Not without effort. If the cabinet is divided up by materials, you could make the existing handle invisible using modify materials and import a separate handle, manually position it and then group the two objects together.

Alternatively you would export your cabinet and use a modelling tool (like Blender) to edit the object there to change the handle, then re-import back into SH3D.

In theory you could create (in an external program) a cabinet with multiple handles all using different materials, and set all but one of them to invisible. Then the user could have a choice of handle. Note that this would balloon the file size though. I don't know for sure if this would actually be possible.