or as somebody on the other veggy food thread suggests , , ,fruit yoghurts 
well yes, everything can be cooked & kept in the oven , but that's not the point of a bbq is it? 
Oh and people who eat fish ARE NOT VEGETARIAN 
I'm sick of being in some dingy pub chain & being offered fish & chips when asking what vegetarian options they do. Or being told that I must eat fish cos 'my *insert distant relative/friend* is one & s/he eats a bit of fish'
sorry rant over 
I would recommend Quorn sausages for a bbq. They are good solid 'meaty' sausages unlike Tesco's own & Linda McCartney brands which are very 'loose' & would pbably fall to pieces.
Again burger wise I'd recommend the Quorn. Same reasoning really. Quorn do 'meat' very well where other brands are more 'unmeaty' if that makes any sense
I know some veggy's are against meat substitutes on principle but they are the best option for a bbq really. Word of warning tho - do you have two seperate bbqs & utensil sets? Going to all the trouble for veggy guests is kind of pointless if you serve up things covered in meat juices!
I can't believe fruit yoghurts are being suggested as meal ideas!
As mentioned above every kid must love Spag Bol surely?
If the Quorn mince isn't to her fussy liking (My bf thinks it's too squishy textured) try Real-Eat Mince, it's readily available, I get it at Tesco.
Meat substitutes like Quorn 'chicken breasts' are great for quick dinners, but try & make some fresh stuff for variety. There are some great veggy recipes listed here. Even check the packaging of fresh veg, a few of my favourites have come from the plastic bag my sweet potatoes were in
Pizza was mentioned above but why not try making your own with her favourite toppings? If you don't feel up to making bases you can buy readymade. A little tomato sauce & mozzarella et voila! (plus your own toppings)
I agree with the people above, the best thing is pea soup. I use Nigella Lawsons recipe which is basically the same as Carl J posted w/out the chilli, but may try that the next time 
The colour & freshness is amazing
