As we know WordPress supports multiple tag queries (',' and '+'). The only problem with this
add_query_arg() doesn't handle these methods if a query param is already exists in the URL.
From the following url
www.domain.com?post_type=ptype¶m=value1 add_query_arg('param', 'value2') will generate
www.domain.com?post_type=ptype¶m=value2 insead of
I would only use comma separated (OR) method. Could you please help me to write a function which adds additional param value next to an exsisting one? regular expressions perhaps?