For the Reply after going to inbox, you want to see who all the recipients are who received the message.
In buddypress plugin, it default is set to max 5, so 4 recipients including you equals 5. On 5 or more recipients it simply states “Conversation between 5 recipients.”
You can use this filter function
add_filter('bp_get_max_thread_recipients_to_list', 'bp_get_max_thread_recipients_to_list_reply');
function bp_get_max_thread_recipients_to_list_reply(){
return 999;
}
It is set to 999, meaning after 999 recipients it will display “Conversation between 999 recipients.” otherwise it will work and autolink to up to 999 recipients.
Change the default return value to whatever number you would like.