From the main menu, head to 'Equity' and select 'Shareholders'.
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In the top right corner, click 'Actions'
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Select 'Convert' from the dropdown menu.
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Choose the relevant Shareholder, the Share Type you are converting from and to (if you haven't created the new share class, you can do so by following the instructions here), the Date of Conversion, Number of Shares and Split Factor (if 1:1 simply enter 1 in this field).
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Click Convert.