Instalment button with several options, can I add some option fields for sizing & text?

[Carled]

 It's not as crazy as it sounds... I'm creating an instalment button with several options for tournament entry. Each player gets a shirt and I need to get them to select shirt size from a drop-down. Also enter some free-form text for printing name on shirt.

I have this set up as a test button in the sandbox, but after experimenting with html variables it just kept breaking the button and no code would be generated so I don't know if what I want to achieve is even possible.  I just want a single drop down and text field after the different instalment plan options basically.

<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post" target="_top">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="xxx">
<table>
<tr><td><input type="hidden" name="on0" value="plan"></td></tr>
<tr><td><input type="radio" name="os0" value ="option_0" checked="checked"></td><td><strong>Full weekend, shared room</strong></td></tr>
<tr><td></td><tr><td></td><td>Number of payments 4</td></tr><tr><td></td><td>
<table>
<tr><th align="left">No.</th><th align="left">Due*</th><th align="right">Amount</th></tr>
<tr><td>1</td><td>At checkout</td>
<td align="right">£50.00 GBP</td></tr><tr><td>2</td><td>after 2 months</td>
<td align="right">£35.00 GBP</td></tr><tr><td>3</td><td>after 4 months</td>
<td align="right">£50.00 GBP</td></tr><tr><td>4</td><td>after 6 months</td>
<td align="right">£50.00 GBP</td></tr><tr><td COLSPAN="3" ALIGN="right">Total   £185.00 GBP</td></tr></table></td></tr>
<tr><td><input type="radio" name="os0" value ="option_1"></td><td><strong>Full weekend, single room</strong></td></tr>
<tr><td></td><tr><td></td><td>Number of payments 4</td></tr><tr><td></td><td>
<table>
<tr><th align="left">No.</th><th align="left">Due*</th><th align="right">Amount</th></tr>
<tr><td>1</td><td>At checkout</td>
<td align="right">£75.00 GBP</td></tr><tr><td>2</td><td>after 2 months</td>
<td align="right">£50.00 GBP</td></tr><tr><td>3</td><td>after 4 months</td>
<td align="right">£65.00 GBP</td></tr><tr><td>4</td><td>after 6 months</td>
<td align="right">£45.00 GBP</td></tr><tr><td COLSPAN="3" ALIGN="right">Total   £235.00 GBP</td></tr></table></td></tr>
<tr><td><input type="radio" name="os0" value ="option_2"></td><td><strong>Saturday night only, shared room</strong></td></tr>
<tr><td></td><tr><td></td><td>Number of payments 4</td></tr><tr><td></td><td>
<table>
<tr><th align="left">No.</th><th align="left">Due*</th><th align="right">Amount</th></tr>
<tr><td>1</td><td>At checkout</td>
<td align="right">£40.00 GBP</td></tr><tr><td>2</td><td>after 2 months</td>
<td align="right">£30.00 GBP</td></tr><tr><td>3</td><td>after 4 months</td>
<td align="right">£30.00 GBP</td></tr><tr><td>4</td><td>after 6 months</td>
<td align="right">£30.00 GBP</td></tr><tr><td COLSPAN="3" ALIGN="right">Total   £130.00 GBP</td></tr></table></td></tr>
<tr><td colspan="3"><i>* We calculate payments from the date of checkout.</i></td></tr></table>
<table><tr><td align=center><i>Sign up for</i></td></tr><tr><td><input type="image" src="https://www.sandbox.paypal.com/en_US/GB/i/btn/btn_installment_plan_LG.gif" border="0" name="submit" alt="PayPal – The safer, easier way to pay online."></td></tr></table>
<img alt="" border="0" src="https://www.sandbox.paypal.com/en_GB/i/scr/pixel.gif" width="1" height="1">
</form>