All Users of a Role Register for Primary Site (multisite)

Would it be possible to add a function that says if someone fills out the registration form for a certain role (subscriber) they are automatically signed up on the primary domain, and nowhere else?

So... If register= 'subscriber' then site = 'primary url'

This is technically the wordpress default, but if you put a GF user registration form on a subsite, they are placed on that site instead of the main site. Is there a way to have GF do it the standard way?

Okay, thanks for the reply.

I am now just trying to setup a redirect so all register links go to the mainsite and then just redirect back to previous page. Is there a way to attach a query string or something like that for the redirect to accomplish this?

I tried this in my function:

<a href="http://hookahi.com/member-join?redirect_to='.get_permalink().'" rel="nofollow">Register</a>';

but the GF redirect overrode it and sends the user to the homepage.

Thanks for that, I think that is exactly what I am looking for. I am a bit of a php noob. Can you tell what I did wrong with this:

add_filter("gform_confirmation", "custom_confirmation", 10, 4);
function custom_confirmation($confirmation, $form, $lead, $ajax){
    if($form["id"] == "11"){
        $confirmation = array("redirect" => wp_referer_field( $echo) );
    }
    return $confirmation;
}

Also I wanted to thank you David for helping me out with this so far

I was getting the same result I think. Okay sounds good, hopefully they could clear it up.

Okay, I think I get it-- I added a ';' after the post input line btw.

All that returned was the word "array" printed? No redirect or anything

All that was outputted was the word 'array' printed in place of the form...

I put $_SERVER['HTTP_REFERER']; (also tried $_SERVER['HTTP_REFERER']) as a default value in a single line text box that was hidden..

I am still getting the same result with the word 'array' printed. I posted my exact code from my functions.php file here: http://pastebin.com/v4wR10AE

SOLUTION: Below is the solution to this problem. If you would like an automatic redirect to the previous page, here is the code to help you out. A very special thanks to David Peralty for this solution.

Insert this code into your functions.php file

add_filter("gform_confirmation", "custom_confirmation", 10, 4);

function custom_confirmation($confirmation, $form, $lead, $ajax){
// replace with the input number of the hidden field
$redirurl = $_POST["input_2"];

    if($form["id"] == "1"){
	$confirmation = array();
	$confirmation['redirect'] = $redirurl;
    }
    return $confirmation;
}

add_filter("gform_pre_render_1", "redirecturl");
add_filter("gform_admin_pre_render_1", "redirecturl");

function redirecturl($form){
 foreach($form["fields"] as &$field){
	if($field["id"] == 2){
		$field["defaultValue"] = $_SERVER['HTTP_REFERER'];
	}
 }
 return $form;
}

Three important points:
--Where you see the number 1 is where you will need to fill in the form ID for the form you wish to apply the redirect
--Add a blank text box to your form, the ID of this box is the number you insert where you see the number 2. This text box is where the form will store your redirect url for after submission
--It is important to A) set that field to be dynamically populated (leave it blank though) and to B) hide it using CSS (add a class to form then add a line like .formclass {display: none;} to your css stylesheet)-DO NOT set it to be visible by admin only, it will not work if you do that.

This works great for combining the User Registration add-on and setting forms to "user must be logged in"--place a link to a user registration form in the error message with this enabled and users will be redirected right back to the form after registering (there is also code on this forum for auto-login that really completes the process).