I would suggest that you consider offering her a buy out over 3 or 5 years.  I was in a similar boat a few years back.  A buddy of mine died and was with another firm.  I offered his spouse a 4 year deal and she took it.  40% payout to her in the 1st. year, 30% in the 2nd., 20% in the 3rd. and 10% in the last.  This was a small book of around $25,000,000 that was all fee-based with an ROA of approx. 1.25%.  She basically got a cash flow of 125k year 1, 93.75k year 2, 62.5k year 3 and 31.25 in the last for a total of 100% of trailing 12.  I also hired her as a p/t assistant to help me transition the book and we basically got close to 90% retention.  5 years later I have everyone of those clients I started with and have grown the book considerably with referrals. 

You were able to buy a book while you were at Morgan Stanley?

aha. =) They let you do that.

Ameriprise is actually very very big with this and even offering loans to advisors to go out there and buy books of business out.