Yes, Jaheira and Aerie have some sort of fight, but that just adds to the roleplaying fun and will not keep you from having the both of them in your party. However, with the three pairs Throntar mentions, it is impossible to keep them both in your party at the same time as they will kill eachother
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Melusine, Archbabe of the OHF and the LH
Your voice is ambrosia