In have built a couple of mda library files which I am then referencing from my main Access application (i.e. using Tools -> References from within the IDE).
Is ther
Why not just place the three MDEs in the same folder on the target system? Access should find the MDE references just fine.
Or are you using the add-in logic with the USysRegInfo table? You don't really need to do that with your own add-ins. Just with developer type add-ins such as Rick Fisher's Find and Replace.
If this isn't working for you then tell us what error messages or symptoms.