$_GET Parameter already exist, replace parameter - wordpress

Question

I have a question im busy with a filter inside of wordpress. Now i have problem i try to explain.
If a visitor select a "single merk" url gonna be ?merk=Brand1 and than option 2 is select "Soort" than the url is gonna be "?merk=Brand1&soort=Soort1" that works.
But if you have select both, than want to change only ?merk=Brand2 than the url is "?merk=Brand2&soort=Soort1&merk=brand1" how can i make it if you switch between the "merk" that "Brand1" replaced to "Brand2".
Here is the code:
foreach ( $allemerken as $merksingle ) { ?>
<?php if(isset($_GET['merk']) && $_GET['merk'] == $merksingle->slug){?>
<i class="fa fa-times" aria-hidden="true"></i> <?php echo $merksingle->name; ?>
<?php }else{ ?>
<?php echo $merksingle->name; ?>
<?php }?>
<?php }?>
<p class="mt-30"><strong>Soort:</strong></p>
<?php
$soorten = get_terms('warmtepompcategorie');
// echo '<pre>'.print_r($allemerken,true).'</pre>';
foreach ( $soorten as $soort ) { ?>
<?php if(isset($_GET['soort']) && $_GET['soort'] == $soort->slug){?>
<i class="fa fa-times" aria-hidden="true"></i> <?php echo $soort->name; ?>
<?php }else{ ?>
<?php echo $soort->name; ?>
<?php }?>
<?php }?>
Ps. sorry for my bad English, but hope someone can help me out!

Answer 1

I have made a function.
And i did it like this:
function replace_get($newname,$newvalue){
$oldvars = $_GET;
$varsnew = $newname.'='.$newvalue;
foreach($oldvars as $name=> $value){
if($name != $newname){
$varsnew .= '&'.$name.'='.$value;
}
}
return $varsnew;
}

Answer 2

To prevent the values from duplicating I would operate on a $_GET array, or its copy for adding or removing the parameters like:
$_GET['soort'] = 'new value'; // adding, modifying value
unset($_GET['soort']); // removing value
and then using http_build_query() for building the URL-encoded query string like this:
$query = http_build_query(array('aParam' => $data));