Today i was sculpting a face and ear separately and i then wanted to join them together. The issue was that with the face it had like 3 sub divisions (detailed versions) and the ear was in a different subtool with also a couple sub divisions.
The tip is to use ZBrush's amazing projectAll and dynamesh tools to be able to combine them while not losing any details.
- duplicate out lowest resolution of face, and ears (helps if ears are in 1 polygroup/colour)
- merge the duplicated low res face and ears into one subtool
- dynamesh (subtool of step 2) .. use as many divisions as needed for the lowest resolution only
- now with just the face detail mesh visible, a) choose the lowest subdivsion of detail face mesh b) highlight the dynameshed subtool, and click on project all. this should put the details onto the combined mesh
- now repeat 4 but this time subdivide (subtool of step 3). That is the combined mesh should get the needed division that will match up with the detail/separated mesh subdivision.
- For the ears (4,5) are pretty much exactly the same. The only difference is a) mask all of the combined mesh except for the ears (this was why polygrouping ear helpful because can easily isolate it -- ctrl+shift click on polygroup to isolate it, mask it, ctr+shift click off of polygroup to bring back all polygroups, ctrl+click off of mesh to invert selection). then repeat the steps of (4,5) remembering to make only the detail ear, and not detail separated face visible.