1. Select the sheet tabs that you want to group. To do this, click on the first sheet tab, hold down the Ctrl key, and then click on the other sheet tabs.
2. Right-click on any of the selected sheet tabs and choose "Insert" from the context menu.
3. In the "Insert" dialog box, select "Columns" and choose the number of columns you want to insert. In this case, you want to insert one column.
4. Click "OK" to insert the column in all the selected sheets.
5. To add a heading in cell D2 of the first sheet, simply click on cell D2 and type in the heading.
6. To have the same heading in cell D2 of the second sheet, make sure the sheet tabs are still grouped, then click on the second sheet tab.
7. Click on cell D2 of the second sheet and type in the same heading.

That's it! You have now added a column in both sheets and added a heading in the same cell of both sheets without having to repeat the process manually.