Copy "Followup" functionality on new button click

Hi,

I am working on leads component. Component name is BT108H_LEA. There is a view LeadOVViewSet. There is a event EH_ONFOLLOWUP. Please see the screenshot below.

Now our requirement is to trigger the same Follow up functionality on another custom button on "Transaction History" Assignment block. Please see the below image.

I know how to create a button here. But how to call above Follow up functionality on this button click.

Thanks,