With regard to you questions, it should be possible to write a VBA procedure that steps through each of the records and changes the OLE object from embedded to linked, but you would need to know the path to each of the linked files. Unfortunately that will not solve your database size issues - whether an object is linked or embedded, Access stores a BMP of the image in the record as well, the the BMPs are huge compared to any of the compressed formats. To really effectively deal with your size issue (and not require switching from database to database), you should store the path to the image as a text string. That should let you store all of the records in one database. As to your security concerns, I assume this is running on a server class PC where user rights can be set so that only authorized users can edit the image files - if not, then that step should be taken post haste.
I can't answer your question on licensing, or convince your technician, but the strategy of storing multiple TIFF images in a single document isn't very wise in my opinion. For one thing, if you need to change one of the images because of an update, you have to pull the whole document and update it. I would redesign the image viewing part of your application so it could be viewed in most any program that supports TIFF images - I think your users would like it better too. They could tell your app what image they wanted and bingo, there it would be. Just my <img src=/S/2cents.gif border=0 alt=2cents width=15 height=15>