Hi YF and George, I humbly apologies, the error is on my part I use a large stock pot which is about 26 pints to the top but i fill it to a mark I made which is 22 pints. I note my recipe says 12 pints! so I must apologise for the typo. So a quarter would be 5 1/2 pints! Which accounts for you problems YF. Sorry

The veg stock amounts are not that important, but the spice ratios and amounts are. If you want you can cut up the veg you have in half and cook each separately, reducing each down to a third and then combining them to reduce further. Now the sticky question about onions, my recipe says put all the veg in and top up with onions, which is not helpful to you guys. However I would still say do the same as you ratios will approximately equate in a cut down version. Onions do not add much flavour but are used mainly for bulk.
As far as the peppers are concerned I just throw in what I have available, which is usually a bag of Tescos Value mixed peppers, I don't use expensive stuff. I don't think it really matters as it is a long cooking/breakdown process, so the only possible difference would be sweetness. (green peppers become red or yellow peppers as the sugar reacts with UV). So if you are using green just add about half teaspoon of light brown sugar or Gur.
Sorry I can't be more helpful as we only cook in commercial quantities. I did get Mark to check my type-up of his recipe and got him to try it and he said it was perfect and all the quantities are correct (I had concerns also you know

) However I am talking to Mark tomorrow and I will ask his opinion on reducing quantities, and post his response..
Good luck, and sorry to cause you this confusion. Please get back to me if you have any other queries.
CP