First off, the Union forces are in a mess. You get a bunch of small Divisions with too many artillery batteries and cavalry. Here is what I do.
Break all the Divisions in the Army of the Tennessee (AotTN) down and rearrange them. Grant should be in command of one stack.
Leave 6 cavalry elements as extras. Set these to Green/Green (passive) and Evade Contact. Five cavalry have one experience star, so you might want to use these. Send one of these to Dyer, one to Madison and another to Hickman to recon what Johnston is doing. Rotate these three out with the three left behind in Ft. Henry to maintain eyes on the enemy. Know your foe.
I arrange the AotTN into 3 mostly infantry Divisions, a cavalry Division and one Artillery Division under Sherman with 15 batteries containing all of the heavy guns and the rest 12 pounders. This left 4 batteries loose in the stack. This gave me 24 of 25 Command points used. Now Grant can march on Humboldt to seize the rail junction. His Army stack alone is stronger than all the units Johnston has.
Split Thomas from Buell's stack and make him a Corps Commander. Rearrange the Army to give him two Divisions with all of the units except the heavy mortars. Send him by rail to Nashville to arrive inside the city with the entrenched garrison. These units will exactly fill out his two Divisions to full strength (a General and 17 elements). Set the supply wagon in Nashville to create a depot. Now Thomas will secure Grant's flank.
Split off the non-ironclad gunboat squadron from Foote and send it to the river zone outside of Nashville. Send the squadron there to meet up with it so that the ships block movement over the river. This should close off the only railroad bridge into KY, in case the rebels get there before Thomas. Send the mortars to Humboldt to meet up with Grant.
McClernand is a recruiting officer. Split him from 1st Division and send him alone by rail to arrive inside of Louisville, so he can recruit. He's not a great General and every little bit helps.
Send Foote and his ironclads to Waverly Run east of Ft. Henry to cork that bottle.
With Humboldt and Nashville under control, The Union can call the shots. Good luck!
I'm the 51st shade of gray. Eat, pray, Charge!