Checkbox checked value with foreach 2 arrays of different size

In your 3rd code-block, you have 2 foreach ... loops.
Forget the first one.
In the second one:

PHP Code:

$ck = in_array($sess_temp['step4'],$lt['id']) ? 'checked' : NULL; 


This single line of code can "calculate" the correct value for $ck. It checks if the $lt['id'] value is in the $sess_temp['step4'] array.

The step4 array is an associative array, but you don't do anything with the $key, so you don't really need that.

The rest of the code seems OK to me.