Hi George,
To answer your first question, it would be possible to have multiple linked environments such that:
PROD creates a linked database for UAT
UAT creates a linked database for TRAIN
TRAIN creates a linked database for DEV
Each system can only directly be linked to one other system. When set up this way, you would first need to migrate from DEV to TRAIN, then TRAIN to UAT, then UAT to PROD.
To answer your second question, although this is possible it could be extremely limiting, because while the systems are linked, no changes can be made except in DEV (or whichever is the last system to be created). When you migrate any one system up the chain, all changes in that system are migrated. In a multi-project environment this is probably not what you want.
An alternative is to use the import/export tools contained within OnBase Studio and Configuration (Utils | Change Management) to move changes between systems. You could still use Configuration Migration to create other systems from PROD (using the Unlinked option).
