Manager Approval for custom Form

Hi,

OneIM version 8.2.1

I have created a custom form copy of VI_Employee_Edit, and the manager field is editable. Users are onboarding through that form. When I submit the form, user provisioning gets triggered. But I want to add manager approval. After submitting the form, it should go for manager approval 1st. Once the Manager approves, then provisioning should trigger.

Can anyone help me with this? How can I add approval in the custom form?

Thanks,