Using Office 365 (Desktop Install) on Windows 10.

I'm trying to create a table with very specific formatting and can't seem to get what I want. I want a column with three rows next to a column with two rows, with each row in the first column at minimum height, and the rows in the second column split half-and-half. (The table itself is larger, but this is the problem area.) To illustrate, what I want is:

But due to minimum row heights applying across merged cells, the best I can come up with looks like this:

Is there any way to solve this? Splitting cells vertically creates an independently movable divisor; is there any way to create the same for a horizontally split cell?