Incorrect Envelope Number Assignment

[LaVerne]

Member A - Env. # 110 Has contributions posted in 2010
Member B - Env. # 111 Has contributions posted in 2010

Envelope Numbers are switched thus contributions are posted to the incorrect person.
When I attempt to reassign the numbers to the correct member, a message is received that I can't do that as contributions are posted to the accounts.

Is there a simple way of accomplishing the correction?

[Zorak]

You must first reassign each of them an available number, like 1110 and 1111. Then 110 and 111 will be available for you to assign to the correct people.