Append the suffix to predecessor element if all its following elements have the suffix in them

Append the suffix to predecessor element if all its following elements
have the suffix in them

I would like to, move(remove from item and append to group) suffix if ALL
the tr(item) in that group have that suffix in their td(index=1) element's
value. That means '[s2]' should be move to Group A and [s1] to Group B
This XML should be:
<table xmlns="MyNamespaceUri">
<tr type="group"> <td index="1">Group A</td> </tr>
<tr type="item">
<td index="1"> Item Type A1 [s1],[s2],[s3]</td>
<td index="2">11</td>
</tr>
<tr type="item">
<td index="1"> Item Type A2 [s1],[s2]</td>
<td index="2">21</td>
</tr>
<tr type="item">
<td index="1"> Item Type A3 [s2],[s4]</td>
<td index="2">31</td>
</tr>
<tr type="total"> <td index="2">63</td> </tr>
<tr type="group">
<td index="1">Group B</td>
</tr>
<tr type="item">
<td index="1"> Item Type B1 [s1],[s2],[s3]</td>
<td index="2">12</td>
</tr>
<tr type="item">
<td index="1"> Item Type B2 [s1],[s3]</td>
<td index="2">22</td>
</tr>
<tr type="item">
<td index="1"> Item Type B3 [s1],[s4]</td>
<td index="2">32</td>
</tr>
<tr type="total"> <td index="2">66</td> </tr>
</table>
Transformed like this:
<table xmlns="MyNamespaceUri">
<tr type="group"> <td index="1">Group A [s2]</td> </tr>
<tr type="item">
<td index="1"> Item Type A1 [s1],[s3]</td>
<td index="2">11</td>
</tr>
<tr type="item">
<td index="1"> Item Type A2 [s1]</td>
<td index="2">21</td>
</tr>
<tr type="item">
<td index="1"> Item Type A3 [s4]</td>
<td index="2">31</td>
</tr>
<tr type="total"> <td index="2">63</td> </tr>
<tr type="group">
<td index="1">Group B [s1]</td>
</tr>
<tr type="item">
<td index="1"> Item Type B1 [s2],[s3]</td>
<td index="2">12</td>
</tr>
<tr type="item">
<td index="1"> Item Type B2 [s3]</td>
<td index="2">22</td>
</tr>
<tr type="item">
<td index="1"> Item Type B3 [s4]</td>
<td index="2">32</td>
</tr>
<tr type="total"> <td index="2">66</td> </tr>
</table>
Thanks a ton in advance.