hello mohabsaleh,
Have you figured it out yet? If not, i would love to help or point you to someone who is a expert at wix code and wix databases. Have you heard of fiverr.com? this guy is amazing and can do anything that you would think is impossible. His direct link is fiverr.com/tiaanrich
If you message him, be sure to let him know that Austin Searle sent you. I am positive that what you are describing with the url part or anything related to your members section of your site, he will be able to help.