I got it. I said you on ICQ that the solution is logical and it proved to be in the end. We were looking for ID conflicts in the wrong place. Those Byza monarchs ids are same as some Vanilla monarchs. By disabling all vanilla monarchs I got it to work at first and after that I just changed all conflicting IDs to be 4XXXX instead of 3XXXX and it ran fine with vanilla monarchs enabled.