Imoen must die *Throne of Bhaal spoilers*

So I was playing ToB again and had killed all five the Bhaalspawn. At this point I was supposedly the only Bhaalspawn left alive and I went to the final boss for the ultimate battle for Godhood. The whole plot surrounded around all the Bhaal essence now being gathered and either Melissan or me would become the new God of Murder.

Then suddenly it occured to me:



My other party member is also a child of Bhaal. Did they overlook this when writing the storyline?

More accurate spoiler warning. -Jalily