I see. Thank looks soo much simpler than messing with a tree view. Thanks MajP!
What you have can be shown in a traditional Form / Subform (parent / children) design. So you have multiple options to display this information. Another possible view is two linked continuous subforms.
A treeview shows it utility when you have hierarchical data with multiple levels. Especially when the amount of levels is variable and no specified limit. I would argue that is near impossible to display logically in any other way.
The Data sheet Sub Data sheet view that you are looking at works fine IMO, but others on this forum think it is too confusing. However I do think if I was using it I would put these data sheets on an unbound form. That way you have some options to put controls and nicer formatting. Also there are some hidden features of datasheets that you can use to format the datasheet better such as setting and locking column widths
Finally I think I would use it only for display and not add and delete. I do think that would be too much and get confusing.