Online Arbitration Portal in PHP

We are looking for expert web developers to build an online portal for Arbitration where the users can register themselves and can do the following: 1. Invite the other party of dispute to initiate arbitration. 2. Secured Chat system with document upload system. (Can add any no of members to chat) 3. Video Chat System (Automated Recording saved in system whose copy is available for download to both the party) 4. User have option to add any no of member to his team before communication and same option for other party too. 5. After the communication, they can create an online mutual agreement and digitally signed that; available to download too in pdf. Need a Good design for whole system and convenient user interface.