Hi DX.ICEBreaker,
Perhaps I'm way off base on this, if so I apologize in advance. Both Excel and Numbers will merge cells but, in Numbers with odd number of merged cells returning back—splitting—to the original number of those merged cells becomes problematic; not in Excel.
As for Excel for the Mac in the help file it reads:
Merge or split cells that span several columns or rows
1. Select the cells you want to merge or the cell you want to split.
2. On the Formatting Palette, under Alignment and Spacing, do one of the following:
• To merge cells in a row or column or both, select the Merge cells check box.
• To split a cell into separate cells, clear the Merge cells check box
There isn't a reference to un-merged cell then splitting it. Some additional Windows Excel 2007 info: You can't split an individual cell, but you can make it appear as if a cell has been split by merging the cells above it. For example, you want to split cell A2 into three cells that will appear, side-by-side, under cell A1 (you want to utilize cell A1 as a heading). It is not possible to split cell A2, but you can achieve a similar effect by merging cells A1, B1, and C1 into one, single cell. You then enter your data in cells A2, B2, and C2. These three cells appear as if they are split under one larger cell (A1) that acts as a heading.
Again if I'm way out of the ball park in what you're explaining do blame it on my tri-focals. I'm dancing as fast as I can...
Sincerely,
RicD