Aggressive stalling of a publication: how do I publish?
I'll provide a different perspective. You do say that they are engaged in the process, ask for things and make changes. That doesn't look to me like they're actively trying to prevent you from publishing. Why would they spend time on the paper at all if their goal is to not have it published?

So, to me it sounds like the problem might at least partially be with you. So be constructive:


Draw up a list of things you still want to change on the manuscripts
Ask them what they still want to change
Create a timeline for this to happen


You're unlikely going to get anywhere by being antagonistic, and you need the papers for your career. So relax your stance, be pragmatic and flexible, and see whether you can elucidate what their concerns are and how they can be overcome through a concrete set of steps everyone can agree upon.