Animal (Cat) Behavioralist

I have 2 sibling DSH cats that I got when they were kittens, now 3 years old. I recently rescued a Bengal who is 4 years old. It’s been 4 months and I’m still having issues integrating them. I have baby gate dividing the first and second floors. I’ve done Jackson Galaxy’s cat integration steps. Currently stuck at Eat, Play, Love. I am now able to have everyone eat together but that’s about it.

The Bengal will chase my 2 other cats whenever he is downstairs, well most of the time. The Bengal will usually start fighting with them and fur will fly. My 2 cats now really dislike him and will growl and hiss at him when he gets near.

I’m not sure what else I can do if I can’t integrate them. The Bengal has lived with another cat in the past.

Any recommendations for a cat behavioralist or tips on how to integrate? He’s a great cat when he’s not around my 2 other cats. I hate to rehome him but will have to if this continues.