It seems quite simple but there is something I am not able to figure out. I hope someone can help me fast.

I have an url, something like <http://host/controller/action/argument/named:1/?query1=1>. I want to add another query param to look it like <http://host/controller/action/argument1/argument2/named:1/?query1=1&query2=2>. I fact I want to add *query2=2* to all URLs on a particular page, through some callback or something.

An URL may or may not have query params in the existing page URL. 

How do I do it?