The answer is yes according to the Post 9/11 GI Bill Memorandum dates 22 JUN 09 from Sec Def on paragraph 3.g.(2)(b) page 17:
An individual transferring entitlement under this section may modify or revoke at any time the transfer of any unused portion of the entitlement so transferred
- An individual may add new dependents, modify the number of months of the transferred entitlement for existing dependents or revoke the entitlement while serving the Armed Forces
- An individual may not add dependents after retirement or separation from the Armed Forces, but may modify the number of months of the transferred benefit or revoke the transferred benefits after retirement or separation for those dependents who had received transferred benefits prior to separation or retirement.
The modification or revocation of the transfer of entitlement under this paragraph shall be made by submitting notice of the action to both the Secretary of the Military Department concerned and the Secretary of the Veterans Affairs. Addition, modifications, or revocations made while in the Armed Forces will be made through the TEB website. Modifications or revocations after separation from the Armed Forces will be accomplished through the DVA.”
Hope that helps for all those veterans who have had circumstances change!