Hi Manuel,
If you think Hannah is really a different person than Harriet, (sometimes used interchangeably) you can add her as another wife. It would be best to have documented info about her beforehand. The current entries are technically unsourced, only from a family tree. You should probably contact the profile manager first.
This will probably raise a question about the first child currently listed as Hannah, it would be strange if a 2nd wife named her child after the first wife...