Hi there,
Yes, there would be no problem using them together. Pancreatitis is either Damp Heat (meaning kibble and processed foods are the issue), Shao Yang disharmony (suggesting a microbiome issue, possibly from too little plant material in the diet) and Blood deficiency.
For acute Damp Heat, I use Si Miao San. Dampening herbs like Cessorex can be stopped if they are not otherwise helping. If Cessorex has helped a lot, then this is a Shao Yang disharmony. Make sure the diet is not pure meat and add some probiotics (Bifidobacterium, Lactobacillus) along with making the diet 1/6 to 1/3 plants. If it's Blood deficiency and the pancreatitis is mild, then Yi Guan Jian (Natural Path Herb Company) should address it. YGJ is compatible with Shao Yang formulas and is often needed as a follow up where the Shao Yang approach is working for allergies.
Hopefully, that's enough to help you sort things out. Simple answer, though: Four Marvels is fine to try with Cessorex. If it helps, the dog is Damp and the next step is to change the diet (whether for pancreatitis or allergies).
Steve