Owl familiar capabilities while executing the Dragon’s Breath cone

I just had a session last night, when I was trying to execute Dragon’s Breath with my owl familiar for the extra damage of course. DM didn’t allow me to fly from one side of the room to the other and start my 15′ cone on the tile of my choosing.

They said the reason was that it was too intricate of a maneuver and that the owl couldn’t fulfill that type of action. The issue is where and how the owl will execute. They are stating that it only obeys commands and that it executes on its own accord basically. I was trying to start the cone on a tile with an enemy and the backspray not hitting my companions and the DM wouldn’t allow it.

Nothing written stated any drawback on this ability. Owl also has Flyby, which should tell you that it is capable of accurate maneuvers. Is my DM correct or can my familiar do this?

This question is not if the owl can perform the cone, that has been granted. But what remains is the intelligence needed to perform “more intricate maneuvers when executing the cone”. Dragon’s Breath should have something there if intelligence score was an issue, if a creature can be gifted the spell it should be able to perform the execution in any way the caster should see fit. IMO. Again all that was commanded of the Owl was to strafe from one side of the room to the other then deliver the cone on the tile of my choosing. How else should the placement of the cone work?