Hi! I'm new in this forum! I wanted to ask, since I am a big fan of this game, which became a kolossal in the following years, I wanted to know how to get in HOMM1 in 1995, this dialog box to how I can customize how many troops can be exchanged with another rider, and/or on a another castle. By which command can I have this dialog? The image is below. Thank you very much if you answer.

If I recall correctly, you need to hold the Shift key as you split armies between two heroes.

Yes, you click into a stack of heroe A and then click into one stack of the other hero while pressing shift key.