So, do you need help in the scenario file, or the units file?
It really depends on what you want to do. You can take an original brigade from the game and apply it (i.e., uni_CSA_Bde2TN) into the scenario file, and then apply the specified units (be aware that in the original game, very few brigades have more than 2-3 regiments, so you must group regiments together, which probably shouldn't be a problem for the Bentonville scenario when a brigade really wasn't a true brigade anymore).
However, if your problem is applying a leader to the division and the brigade, then you cannot do it. A unit can only have one commander, a divisional or brigade commander, not both. So, you have to choose if the brigade will be in a division under the command of Stevenson, or a brigade under Palmer (not both).
I am still not quite sure of your problem...
Best I can do is to cut and paste what is in the Scenario XLS file I have for my mod... Be aware that the units are different sized, and therefore can fit in more actual regiments.
USA 4th Division Group LAND NULL NULL 0 $Prince George's, MD 0 0
USA Theodore Runyon StartUnit|3|uni_USA_Runyon NULL NULL 4th Division NULL NULL NULL NULL
USA Johnson's Bde. uni_USA_VolBMBde NULL NULL Col. A.J.Johnson 1st New Jersey Mil.|2nd New Jersey Mil.|3rd New Jersey Mil.|4th New Jersey Mil. NULL NULL NULL
USA Montgomery's Bde. EndUnit|uni_USA_BdeBM12NJ 4 NULL Col. Montgomery 1st New Jersey|2nd New Jersey|3rd New Jersey|4th New Jersey NULL NULL NULL