Is it possible on the Invite Friends page to have a standard message versus an open field where people type their own brief message?
It's already implemented that way.
Open any of the 16 language files in components/OssnInvite/locale
and you will find two entries:
1. 'com:ossn:invite:mail:message' : this one will be used when people enter an individual message
and
2.'com:ossn:invite:mail:message:default' : this one will be used when people leave the field blank.
Due to the many requests in the past for additonal features and components we have decided to develope a premium version. Features like Hashtags, Videos, Polls, Events, Stories, Link Preview, etc included in it.
$199 (Life Time)