The only workaround is to have a competent agent remove the initial FFP details and then add the new FFP details. The FQTV field can hold multiple numbers, so most interfaces only allow you to add another number, NOT to remove the numbers that may already be found in that field.

The better workaround is not to add an FFP at all, and/or use strategies or purchase tickets that do not require you to change horses mid-race