"In a split FE/BE database system, do I have to secure each of the FE's
independently, or can I do it just once?"
If so, the answer is yes. Secure the master copy of the FE, on your PC,
using the master MDW. Then distribute to each FE user:
- a copy of the FE;
- a copy of the MDW, and
- a shortcut which will open the FE using that MDW.