Sub Items Creation in other Board

While working for a client who is working with different brands onboarding where multiple stages are there and for each stage there are multiple meeting. Now the client wants to see all the meeting notes and ongoing process in one board.
All the meeting notes is import from a excel sheet in one board and want to create the view by moving the items in the earlier board in the form of subitem that will reduce the number of column and more number refrain from creating more no. of boards.