Vendor migration

[Vijayalaxmi Kudekar]

Hello,  I am working on migrating a client from one HISP service provider to another HISP service provider, but it seems one needs to migrate all the customers in one go - due to DNS delegation structure. This is really difficult for us to migrate all customers at once. Can someone please suggest any alternatives?

Note: We do not want to change the DIRECT address of the providers

Thanks