Can I take control at a certain moment in a game replay and engage in a completely new battle with the AI?

I just started playing this game and I'm not very familiar with the game's features and controls. I tried to control my units using /cheat in a replay, but the recorded actions from the replay are still being carried out, and when the replayed actions end, the AI does not continue to act.

How can I achieve the effect I want? I would be very grateful if anyone knows the answer and is willing to help.

Only thing I've noticed is if the player active the cheats and global spec control, then, in the replay you can control units.
But as soon as player or AI issue an order, it will be applied and cancel the spec order.
Replay file is just a list of orders to units I believe.