保留律师作为移民签证代理？

EB1A petition已经批准了，下一步是走CP的流程。律师WG，他们问我需要retain them as IV application.

If you choose to proceed with your IV application on your own instead of retaining us, please contact NVC (https://nvc.state.gov/inquiry) to remove us as the attorney-of-record for your IV application and add yourself as the agent. Please note that we will not be able to provide any advice or assistance regarding your immigrant visa processing if we are not retained. If you wish to retain us for your IV application, please keep in mind that we can only be retained before your DS-260 is submitted. Thank you.

这个服务要1800刀，似乎也没啥难度。