Is representing an heir and also representing the executor for the estate a conflict of interest?

My sister's attorney was chosen by the executor for my mother's estate to serve as attorney for the estate also. Now I'm being ganged up on by my sisters attorney and the executor. This is in CT. I told my attorney this has to be a conflict of interest. But he just shrugged it off saying "that's the system." I tried looking on the CT Bar oc website but there is nothing useful there for the public. Any thoughts about this? Is it a COI?