Provider needs to move customer, that belongs to Reseller1, to the Reseller2.
The operation seems to be not possible due to the error:
The transfer cannot be performed since there are subscriptions that are based on the service plans not delegated to the new vendor:
According to the feature requirements:
(Accounts Transfer Requirements) http://download.automation.odin.com/oa/7.2/oapremium/portal/en/billing_provider_guide/79948.htm
All customer's subscriptions are based on service plans that have common ancestor (in terms of plan delegation) under both vendors.
In case of Power Resellers, both of them may order the same resources from provider, create similar Service Plans, however it is currently not possible to move subscription between separate service plans.
Feature request PFR-626 (Moving Subscriptions to a new Reseller Account) has been submitted to support such functionality.