Agree with Terry. not a cake walk.
Combining linkage service and identity columns is a permutation you might want to avoid by either
1) not using the linkage service for your update screen and propogate the primary master keys in the post update event or by
2) not using identity columns for primary keys that have foreign keys hanging off it. (That was my solution recently - 1997 - Identity columns mainly intended for transactions perhaps not master files...)
3) update (insert) the primary table rows in a different transaction before creating dependent table rows
PS: There will be other challenges if/when you start inserting and deleting in one go too, but pfc update style might help you there.
Good Luck,
Lars 