Opportunity and Appointment have XBO extend field, how to transfer value when create?

Hi experts,

I created the xbo object in the following workcenter:

．Appointment

．Task

．Lead

．Opportunity

Extending the data type field.

When I Activities tab in opportunities create the Appointment.

The system will automatically transfer some of the default values from opportunities.

For example, the Subject(Name), Account, Primary contract

I would like to extend the field of transfer default value from Lead or Opportunity.

1. How do I determine is create under Lead or Opportunity work center, Activities tab create Appointment or Task job?

2. How can I get default?

Can provide me any ideas or information?

Thank you very much.

Best regards,

Daniel