Holly and Ivy are on JWB lamb and rice and have no issues at all.
I give them the lamb and rice in preference to the chicken recipe.I'd stop the chappie for a while and keep him away from anything with chicken in it. I just found royal canin too expensive in comparison.Arden Grange is another food with similar hypoallergenic formula to JWB.
In Jasper's case,maybe have a chat with the vet about a prescription diet like Royal canin gastro enteric.It's used in long term management of pancreatitis and persistent dodgy tummies.You have to really feel for him at his age,he's such a great little dog.
Sharing my sofa with Holly, Ivy,Lilly and Hazy.. and never forgetting our beautiful Daisy who reached the bridge too soon.