This is a (woolly) mammoth task

After making Little Miss's cardi my mum asked if she could have one ...... yeah of course she can ........... except the pattern I have only goes up to 3-4 years and lets just say mum's needs to be a little larger than that! So now I'm winging it really, adapting the pattern to fit a UK size 20-22 and hoping for the best. So far I've finished the back panel and made a start on one of the front pieces but I'm gonna need some serious PMA to get this to work. That said, I'm going to be soooooooo smug if it works out in the end ..... watch this space!