First, you may wish to consider getting your Dad on fish oil with EPA and DHA. One study suggested 2.2 grams of EPA and 1.4 grams of DHA. According to the lit, It will help stabilize weight, increase lean mass, improve appetite and help him feel stronger. I've got three or four medical journal articles here all referencing it and it has worked with my Dad. His weight has increased from time of diagnosis and he feels better. He also had several liters of fluid in the abdomen, they tapped the fluid using CT to guide the process and he felt sooo much better afterward. We were told the Gemzar was not working based on CT but I read a study suggesting that CA-19-9 markers tended to be 2-9 months ahead of the scans. Based on the scan the doc was going to discontinue treatment. He changed his plan as we questioned the CA-19-9 having gone down and much to our delight his latest scan has caught up and the tumors regressed. Additionally, I've read many,many studies about the effects of green tea on pancreatic cancer. I have him drinking 2-3 cups a day. There's a fair amount of evidence pointing to potential efficacy of green tea- but the biggest thing I think is important here is that even though our medical team dismisses the green tea, they all agree it can't hurt.
In short, based on my limited experience here (no medical training) I would suggest, second opinion, fish oil capsules, protein shakes (high calorie, low sugar), fluid tap, green tea with high levels of EGCG and pay attention to CA-19-9 not just scans to determine efficacy of treatment.
Never heard about chemo being dependent on billi scores, but again I have very limited knowledge.