Can't immediately find the quantities, but my mum passed on a great BBQ sauce which used the following ingredients. I've made it several times, but I do it 'to taste' anyway. Try a tablespoon of each of the sauces and sugar here, to 1 onion, 1 tin toms and 1 clove garlic and you'll be close. Adjust to taste. Reduce (boil off) as desired for stickiness. It's all about the balance of the white wine vinegar vs the sugar, I think, and tasting as you go.
Finely chopped onion
Tinned chopped tomatoes
Soy sauce
Worcester Sauce
White wine vinegar
Brown sugar
Salt&Pepper
Garlic