HI Shreya,
There should be a context (object A) for the add attributes button, like a surrounding dataview. Place a listview in the dataview with object B over association. On press of ‘add’ you need a microflow with context object A as input parameter and create a new object B and set association with your object A. Refresh object A at the end of the microflow. In your domain should be an association from B * to 1 A.
Under the remove button you place a microflow with object B as inputparameter. Delete object B in the microflow with a refresh in client true.
That should be it.