Writing to new clients acquired on a merger

I was asked for my advice recently ie: What should be in the letter that an accountant was sending to the clients of the old practice that he was acquiring through a merger (in reality it was more of a mergeover).

I suggested that the starting point was to consider what the clients would want to hear/see and what messages the accountant wanted to get across.

The accountant said he wants clients to:

• confirm they'll continue to pay him at least what they paid the predecessor practice
• supply all their information promptly
• not phone him daily
• pay extra fees if they supply tax return information in January
• not look around and move elsewhere without giving him at least a chance

We concluded none of the above could go into the first letter from new accountant!

What would you like to say to new clients acquired on a merger, takeover or mergeover?