Adding new insert mesh/Append mesh

Hello I am a beginner mostly to Zbrush. Is there a way I can add a custom mesh to the insert sub-tool/ append sub-tool list?append.JPG

You must first load/import (load for .ztl, import for .obj) the mesh you want to append into your program session. It will then appear in the tool list. You can then insert/append it to the desired tool when that tool is active.