Best I can suggest that sometimes it can be worthwhile to push with your ally in the initial stages of the game. Especially on a map like rails and metal or any map that more or less has a 'side' for each team.
The benefits of harassing your opponents resources often aren't worth having your own cut off.
Now this won't help a player ally that outright loses their first whole squads in the initial engagements. In coh2 it is more important to get resources yourself than it is to deny your opponents resources.
But you might be able to get a faust off or cover a flank to keep things afloat. That can go a long way.
