<| 1-> 
{
 {{0.1,2.1},{0.2,-6.4},{0.5,-8.2}},
 {{0.1,4.2},{0.2,0.7}, {0.5,-3.5}},
 {{0.1,5.6},{0.2,5.5}, {0.5,0.2} },
 {{0.1,7.4},{0.2,7.2}, {0.5,3.1} }
},
2-> 
{
 {{0.1,4.5}, {0.2,-2.5},{0.5,-7.4}},
 {{0.1,-3.1},{0.2,1.4}, {0.5,0.2} },
 {{0.1,1.3}, {0.2,3.4}, {0.5,4.27}},
 {{0.1,-3.6},{0.2,3.5}, {0.5,5.6} }
},
3-> 
{
 {{0.1,-3.7}, {0.2,1.3},{0.5,-6.2}},
 {{0.1,-1.4},{0.2,3.4}, {0.5,2.4} },
 {{0.1,2.3}, {0.2,5.6}, {0.5,5.4} },
 {{0.1,3.6}, {0.2,7.2}, {0.5,9.1} }
}|>

<| 1-> 
{
 {{0.1,2.1},{0.2,-6.4},{0.5,-8.2}},
 {{0.1,4.2},{0.2,0.7}, {0.5,-3.5}},
 {{0.1,5.6},{0.2,5.5}, {0.5,0.2} },
 {{0.1,7.4},{0.2,7.2}, {0.5,3.1} }
},
2-> 
{
 {{0.1,_3.6}, {0.2,-2.5},{0.5,-7.4}},
 {{0.1,-3.1},{0.2,1.4}, {0.5,0.2} },
 {{0.1,1.3}, {0.2,3.4}, {0.5,4.27}},
 {{0.1,4.5},{0.2,3.5}, {0.5,5.6} }
},
3-> 
{
 {{0.1,-3.7}, {0.2,1.3},{0.5,-6.2}},
 {{0.1,-1.4},{0.2,3.4}, {0.5,2.4} },
 {{0.1,2.3}, {0.2,5.6}, {0.5,5.4} },
 {{0.1,3.6}, {0.2,7.2}, {0.5,9.1} }
}|>

I want to sort each column in ascending order, so that the first row will now contains the lowest values of f(x), while the last row will contain the highest. Instead, the elements in the row should not change position, so that all the elements in a column keep having the same value of x.
The rows will then be used to create a function that represents the envelope of the different outcomes of a Monte Carlo method.

<| 1-> {{{0.1,2.1},{0.2,0.7},{0.5,-3.5}},
{{0.1,4.2},{0.2,5.5},{0.5,3.1}},
{{0.1,5.6},{0.2,-6.4},{0.5,0.2}},
{{0.1,7.4},{0.2,7.2},{0.5,-8.2}}},
2-> {{{0.1,4.5},{0.2,3.5},{0.5,5.6}},
{{0.1,-3.1},{0.2,1.4},{0.5,-7.4}},
{{0.1,1.3},{0.2,3.4},{0.5,4.27}},
{{0.1,-3.6},{0.2,-2.5},{0.5,0.2}}},
3-> {{{0.1,3.6},{0.2,7.2},{0.5,9.1}},
{{0.1,-1.4},{0.2,1.3},{0.5,5.4}},
{{0.1,2.3},{0.2,3.4},{0.5,2.4}},
{{0.1,-3.7},{0.2,5.6},{0.5,-6.2}}}|>

I want to sort each {x,f_m(x)} in a column in ascending order by f(x), so that the first row will now contains the lowest values of f(x), while the last row will contain the highest. Moreover, the elements should stay in their original column, so that all the elements in a column keep having the same value of x.
The rows will then be used to create a function that represents the envelope of the different outcomes of a Monte Carlo method.

<| 1->  
{
 {{0.1,2.1},{0.2,0.7}, {0.5,-3.5}},
 {{0.1,4.2},{0.2,5.5}, {0.5,3.1} },
 {{0.1,5.6},{0.2,-6.4},{0.5,0.2} },
 {{0.1,7.4},{0.2,7.2}, {0.5,-8.2}} 
},
2->  
{
 {{0.1,4.5}, {0.2,3.5}, {0.5,5.6} },
 {{0.1,-3.1},{0.2,1.4}, {0.5,-7.4}},
 {{0.1,1.3}, {0.2,3.4}, {0.5,4.27}},
 {{0.1,-3.6},{0.2,-2.5},{0.5,0.2} } 
},
3->  
{
 {{0.1,3.6}, {0.2,7.2},{0.5,9.1} },
 {{0.1,-1.4},{0.2,1.3},{0.5,5.4} },
 {{0.1,2.3}, {0.2,3.4},{0.5,2.4} },
 {{0.1,-3.7},{0.2,5.6},{0.5,-6.2}}
}|>

and I want to obtain something like this

<| 1-> 
{
 {{0.1,2.1},{0.2,-6.4},{0.5,-8.2}},
 {{0.1,4.2},{0.2,0.7}, {0.5,-3.5}},
 {{0.1,5.6},{0.2,5.5}, {0.5,0.2} },
 {{0.1,7.4},{0.2,7.2}, {0.5,3.1} }
},
2-> 
{
 {{0.1,4.5}, {0.2,-2.5},{0.5,-7.4}},
 {{0.1,-3.1},{0.2,1.4}, {0.5,0.2} },
 {{0.1,1.3}, {0.2,3.4}, {0.5,4.27}},
 {{0.1,-3.6},{0.2,3.5}, {0.5,5.6} }
},
3-> 
{
 {{0.1,-3.7}, {0.2,1.3},{0.5,-6.2}},
 {{0.1,-1.4},{0.2,3.4}, {0.5,2.4} },
 {{0.1,2.3}, {0.2,5.6}, {0.5,5.4} },
 {{0.1,3.6}, {0.2,7.2}, {0.5,9.1} }
}|>