You can group all your sheets together, so that whatever you do to one
sheet is done to them all - you must remember to ungroup them at the
end.

Assuming all your sheets are contiguous, then click on the first sheet,
hold down SHIFT and click on the last sheet. (If they are not
contiguous you will have to hold down CTRL instead of SHIFT and click
on each one). Then you can highlight the row in the visible sheet and
Insert | Row - this will be inserted at that position in every sheet
which is part of the group.

To ungroup the sheets right-click on one of the sheet tabs.

Hope this helps.

Pete