Multiple Tabs in Table Cell

Hello,

The image below is a screenshot of the heading row of a table. This table is in a Word document, and I am trying to recreate the table in FrameMaker.

I'm only having trouble with the heading row in FrameMaker. Below is a screenshot of my best try. I created two rows for the heading, but maybe there is another way to go about this. One issue I'm running into is the white line between the 1st and 2nd rows across the 12 small columns. The other issue is that I can't make the right border next to the text in the 2nd row disappear (nor the left border next to the far line of text in the 2nd row).

In Custom Ruling and Shading, when I apply the "Invisible" Ruling Style to the top of the 12 small columns in the 2nd row, I get the white line. I wish I could just straddle the rows to fix this problem, but that throws off the alignment of the text in the 2nd row.

For some reason, I'm not able to change the right border next to the text in the 2nd row or change the left border next to the far line of text in the 2nd row at all using the Custom Ruling and Shading Ruling Styles. I've tried applying the "Invisible" Ruling Style, but  nothing changes when I do.

Has anyone encountered something like this before?

Thank you,
Cameo