Linking custom BO with standard BO

Hi,

I have to embed custom BO into standard BO as a new tab.

This is done by creating Embed component object. Now I need to allow user entering multiple values in this new tab .

I have created node and included elements in it, defined cardinality as [0,n].

Also I have defined alternative key as the key field of stadnard BO(Appointment).

When I enter and save data in custom BO now, it says, appointment ID missing,save failed.

As per the error I can see that it is expecting the apointment guid to be filled in the custom BO.

Can you please suggest how to fill the appointment  guid in the custom BO?

I have tried filling this value using data operation and binding Inport parameter of custom BO with the alternative key element of custom BO, it didn't help.

Thanks

Jayasri