Being able to see an invoice after creating with api?

[VirtualSims]

Hello,

 

I am creating orders with the WHMCS API but I want users to be able to see their invoice after as seen here "whmcs/viewinvoice.php?id=7".

 

Is there a way to allow users to be able to see that without having them log in?

 

My problem is that I already have another login database that these users operate from but I decided to get WHMCS to help manage billing, so far things are great other than not being able to have them go from my website automatically into WHMCS without making the users log in twice.

 

Is there any way to fix this?

 

Thanks,

Chris