Because the default sort plugin does not support per row settings, you will need to hack your logic in, using custom sorter and custom marker.
$('table').footable({
sorters : {
alpha : function mysorter ( a, b ) {
if ( ! mysorter.top ) {
mysorter.top = $('table .footable-sorted-desc').length ? 1 : -1;
setTimeout( function(){ mysorter.top = 0; }, 0 );
}
if ( a.indexOf( '\u2063' ) >= 0 ) return mysorter.top;
if ( b.indexOf( '\u2063' ) >= 0 ) return -mysorter.top;
return a > b ? 1 : ( a < b ? -1 : 0 );
}
}
});
<link href="http://fooplugins.com/footable/css/footable.core.min.css" rel="stylesheet"/>
<link href="http://fooplugins.com/footable/css/footable.metro.min.css" rel="stylesheet"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script src="http://fooplugins.com/footable/js/footable.js"></script>
<script src="http://fooplugins.com/footable/js/footable.sort.js"></script>
<table><thead><tr><th>Name<th data-sort-initial="true">Number</thead><tbody>
<tr><td>Average<td>4.5⁣</tr>
<tr><td>Jim<td>5.0</tr>
<tr><td>Sam<td>4.0</table>
Here I am using the Invisible Separator \u2063
to mark the 'top' content.
A few extra lines are used to optimally detect sorting direction and adjust the result accordingly (smallest when ascending, largest when descending).