pass paramter that is a url with parameters

I have a url that have some parameters, one of them is a url e.g www.example.com?p1=v1&p2=v2&p3=url&p4=v4...

the url i want to add has few parameters. how can i add them to this url? becuase from the second parameter the first url take them

e.g www.example.com?p1=v1&p2=v2&p3=www.example2.com?p21=v21&p22=v22&p23=v23&p4=v4...

p21,p22,p23 belongs to the second url (www.example2.com) but the first url (www.example.com) taking p22, p23 has it's own

Thank you for your help