sculpting - how to add new mesh to a wip

just say I tried to sculpt a rat. but the rat looks more like a bat! so now I want to add wings.
how do I attach new mesh to the bat for wings?

what is best way to approach this so that the new mesh is “attached” to the bat and the clay will be merged?

Go to edit mode and change the base mesh to create wings
Or use dynamic topology with something like the snakehook brush

If you have made the creature as one object and the wings as another you can merge the wings onto the bat afterward by first selecting the wings, then Shift+selecting the bat, then Ctrl+J to Join the two.
This will not make them one geometry, you’ll probably need to manually weld the verts after that. But it’s the first step if each mesh is its own Object.