Converting an awning to a three quarter awning

Hi has anyone successfully converted an awning into a combi / three quarter awning. I have a size 12 NR Pullman awning complete with annexe it's oldish (2004) but still in very good condition it's to small for our current van but the size of the actual awning will be ideal, so I am thinking of converting it.. Has anyone done this as a DIY project if so how did you do it & what if any problems did you come across.

JimD