Megillah 15b records three opinions as to how many children Haman had:
- Rava: Ten died in childhood, ten died at the end of the Megillah, and ten were reduced to poverty, totaling 30.
- Rabbanan: There were seventy reduced to poverty, totaling 90.
- Rami bar Abba: There were 208 in total.
I don't see how this is possible, even according to Rava, unless Haman had wives in addition to Zeresh.
Now, various commentaries indicate that the ten sons killed at the end of the Megillah were, in a sense, more important than the others. For instance, R' Elisha Galiko writes:
ועוד אני מדקדק שכתב את בכל אחד ואחד לומר כי כל אחד מהם היה כחמש מאות איש הידועים ההרוגים עם היות שהיו כולם חשובים ושרים
And I infer further that it writes את by each one to say that each one was like the 500 known men who were killed, in that they were all important and officers.
Now, of all of Haman's wives, it's Zeresh that he repeatedly turns to in the Megillah for advice; while he also calls other family and friends, Zeresh is the only one who's singled out. She's not the only one who actually gives advice, and she's singled out even before anyone opens their mouths. Maybe Haman singles her out because she's the most important of his wives... and maybe Haman's ten sons who were so important were specifically her children?
Am I totally off-base here, or is there any merit to this line of logic?