I believe its 17-50 Tamron?
Don't go for the ultra zooms, the IQ is really bad... unless you have an awful stigma for changing lenses. Kit lens + a 55-250 (or 55-200 if you're nikon) can easily give you double the quality at the same or lower price.
Truly speaking, 17-50 F2.8 overlaps 50mm F1.8, generally you will still stop down near F2.8 for portraits with the 50mm... that lens shouldn't be overused wide open.
As for your TFCD... I believe they're friendly photoshoots... perhaps you can consider the Tamron 28-75mm F2.8 or Sigma 30mm F1.4 (different use) otherwise, do consider asking your friends to let you explore what focal length you need. What do you have at the moment?