Complete a WP plugin that is 90% already done

I have a WP plugin which allows registered WP users to send private messages to each other. The plugin also allows attachments with messages. The entire plugin UI is Ajaxified and the Angular JS framework was used by the previous dev (now sick for a long time, hence this post!). The plugin is already functional and allows users to send messages to each other(individuals) and to groups. The remaining work is as follows: 1) Allow multiple selections in the "To" field when composing a message. This multiple selection may comprise of individual users and/or groups. 2) In selecting the recipient(s) of the message the user must be presented with a pop-up in which all the registered users on the WP website must be represented in their individual groups or as individuals if they do not belong to a group. Now the user can either check/select an entire group in which case all of the group members will receive the message and/or select a few members from the group and then select members from other groups or individuals - basically allow various permutations and combinations in selecting the recipients. For those who understand what this will involve and are confident of being able to achieve the desired results, please do express interest. Thanks. P.S. I will upload the plugin in its current state later.