Those ships *are* huge (at least the REF and Meltran ship are, with the 

Mordred at ~1.5 Km in length and the Meltran ship ~4Km)  The Invid ship 
is small by comparison.  WHich is why I didn't consider it possible for 
"nudging" by outside forces.<<

I'm not sure the Bab5 defense grid can destroy anything that big. And is there a typo in the last sentence?

and yes, you are right... The zentraedi *are* expecting outside help once 

they abandoned their ship - but not from Bab5... it's just a convenient 
staging area.  more as the story develops.<<

And just _how_ is the help going to arrive? They're not in the same universe anymore you know. And they're not in the same time zone either. Robotech takes place in the 21st century and Bab5 happens in the 24th.