Hi Jason,
I think I may have found the solution by combining the use of php and css. I duplicated the select menu, then hide the first select menu, if there is no version option, both with php and css. The other select menu only shows, if there is a version option (with php).
It is probably very unconventional, and took me a while to figure out. Serious programmers will probably cry out in horror, but here is the code I used. It works for me, but if there is something, that should not be done, could you please let me know?
<p>
                  <?php if ($row_rsversion['version_id'] == "13") { // Show if recordset empty ?>
                    <select class="<?php echo $tmpElementClassVersion; ?> name="SelectVersion" id="SelectVersion" onchange="WA_FilterAndPopulateSubList(rssize_WAJA,MM_findObj('SelectVersion'),MM_findObj('SelectSize'),0,0,false,': ');showprice()">
                      <?php
do {  
?>
                      <option value="<?php echo $row_rsversion['version_id']?>"<?php if (!(strcmp($row_rsversion['version_id'], $row_rsversion['version']))) {echo "selected=\"selected\"";} ?>><?php echo $row_rsversion['version_compound']?></option>
                      <?php
} while ($row_rsversion = mysql_fetch_assoc($rsversion));
  $rows = mysql_num_rows($rsversion);
  if($rows > 0) {
      mysql_data_seek($rsversion, 0);
      $row_rsversion = mysql_fetch_assoc($rsversion);
  }
?>
                    </select>
                    <?php } // Show if recordset empty ?>
                    <?php if ($row_rsversion['version_id'] != "13") { // Show if recordset not empty ?>
                    <select name="SelectVersion" id="SelectVersion" onchange="WA_FilterAndPopulateSubList(rssize_WAJA,MM_findObj('SelectVersion'),MM_findObj('SelectSize'),0,0,false,': ');showprice()">
                      <?php
do {  
?>
                      <option value="<?php echo $row_rsversion['version_id']?>"<?php if (!(strcmp($row_rsversion['version_id'], $row_rsversion['version']))) {echo "selected=\"selected\"";} ?>><?php echo $row_rsversion['version_compound']?></option>
                      <?php
} while ($row_rsversion = mysql_fetch_assoc($rsversion));
  $rows = mysql_num_rows($rsversion);
  if($rows > 0) {
      mysql_data_seek($rsversion, 0);
      $row_rsversion = mysql_fetch_assoc($rsversion);
  }
?>
                    </select>
                    <?php } // Show if recordset not empty ?>   
                  </p>
                  <p>
                      <?php if ($row_rssizedefault['size_id'] == "8") { // Show if recordset empty ?>
                    <select class="<?php echo $tmpElementClassSize; ?> name="SelectSize" id="SelectSize" onchange="showprice()">
                      <?php
do {  
?>
                      <option value="<?php echo $row_rssizedefault['size_id']?>"<?php if (!(strcmp($row_rssizedefault['size_id'], $row_rssize['size']))) {echo "selected=\"selected\"";} ?>><?php echo $row_rssizedefault['size']?></option>
                      <?php
} while ($row_rssizedefault = mysql_fetch_assoc($rssizedefault));
  $rows = mysql_num_rows($rssizedefault);
  if($rows > 0) {
      mysql_data_seek($rssizedefault, 0);
      $row_rssizedefault = mysql_fetch_assoc($rssizedefault);
  }
?>
                    </select>
                    <?php } // Show if recordset empty ?>
                    <?php if ($row_rssizedefault['size_id'] != "8") { // Show if recordset not empty ?>
                    <select name="SelectSize" id="SelectSize" onchange="showprice()">
                      <?php
do {  
?>
                      <option value="<?php echo $row_rssizedefault['size_id']?>"<?php if (!(strcmp($row_rssizedefault['size_id'], $row_rssize['size']))) {echo "selected=\"selected\"";} ?>><?php echo $row_rssizedefault['size']?></option>
                      <?php
} while ($row_rssizedefault = mysql_fetch_assoc($rssizedefault));
  $rows = mysql_num_rows($rssizedefault);
  if($rows > 0) {
      mysql_data_seek($rssizedefault, 0);
      $row_rssizedefault = mysql_fetch_assoc($rssizedefault);
  }
?>
                    </select>
                    <?php } // Show if recordset not empty ?>
                  </p>

