It's been a while we are looking into this and we haven't come up with an elegant solution. I bought all the necessary components (Amember pro with Joomla pluggin, 1 shoppingcart add-on). Spottedhaggis configured the following for us: Amember registration page [1st form]--> 1 shoppingcart order page [2nd and 3rd form]--> Paypal payment processing [4th form, pre-populated]--> 1 shoppingcart postback to Amember --> Access to Joomla. The problem with this flow is that the user have 3 to 4 forms to fill and they could abondonned any time after the 2nd/3rd form in 1shoppincart. After many discussion with spottedhaggis we believe that there might not be any other flow But I believe that we haven't tried hard enough so I am actually thinking of the following flow: 1 shoppingcart order page [1st and 2nd form]--> Paypal payment processing [4th form, pre-populated]--> 1 shoppingcart postback to Amember --> Access to Joomla. The later flow is only possible with 2 conditions: 1) A unique username and password to be generated in 1shoppingcart each time a product is bought 2) Tha later username+password is compatible with Amember registration 3) 1shoppingcart postback should trigger an automatic sign-up in Amember. Any ideas?