When a member of another lodge/chapter wants to join yours, go to Membership > Add Affiliate in the menu to add them. (If this option is not available in the menu, contact your Grand Office for instructions.)
The Add Affiliate form is a two-part form. The first part looks like so:
After enter the affiliate's member number and date of affiliation, click 'next'. You'll then see part two:
The second part shows you the member and their status in their current memberships. If the member is allowed to affiliate, you'll see a 'confirm' button. Clicking that button will make them an affiliate.