How to send notification to assignee and add as team member from Event Model?

Summary:

We have created a custom status and event within the Event Model. During this event, we automatically assign the assignee and update the user status through a Groovy script. Below is the Groovy script we used in the entry action of the custom event:

UserStatusCode='LAWYER_ASSIGNMENT'
AssigneeId = 1000000644XXXX
AssigneeType = 'OKX_RESOURCE'
adf.util.sendNotification(adf,"Contract Assigned",AssigneeId)
eventModel.execute('createHistory')

System is able to assign the assignee but does not send any notification to assignee (unlike using Assign User action - "Notify Assignee" functionality).

At the same time, we would like to add this Assignee as team member (like using Assign User Action & select "Add assignee to Contract Team" functionality)