Yes, you can create a parent/child relationship between rows in Excel by using the Group feature. Here are the steps:

1. Select the rows that you want to group together.
2. Right-click on the selected rows and choose "Group" from the context menu.
3. A new row will be inserted above the selected rows with a grouping symbol (a number) in the left-hand margin.
4. Click on the grouping symbol to collapse or expand the group of rows.
5. Repeat steps 1-4 for each group of rows that you want to create.

When you sort the spreadsheet, the child rows will maintain their relationship to the parent/header row. However, keep in mind that the grouping symbols will move with the rows, so you may need to re-group the rows after sorting.

Another option is to use the "Outline" feature, which allows you to create a hierarchical structure of rows and sub-rows. To use this feature, select the rows that you want to group together and click on the "Group" button in the "Outline" group on the "Data" tab. You can then use the "+" and "-" symbols in the left-hand margin to collapse or expand the outline. When you sort the spreadsheet, the outline will be maintained.