By Shiva.Carrelo 2016-07-16 21:51:27
I don't think it's possible. Typing /? returnfaith in game returns the following:
USAGE: /returnfaith, /refa [subcommand]
→Dismisses alter egos.
>>Subcommands:
all: Dismisses all of one's alter egos.
Dismisses targeted alter ego if no subcommand is specified.
May be used with placeholders.
The command /returnfaith <p5> will release the 6th member of your party in the same way as /returnfaith <name> (e.g. /returnfaith Moogle), but both of these functions seem to be disabled while you're engaged.
/returnfaith <stpt> will allow you to scroll through your party roster and release the member of your choice, but also doesn't seem to work if you're engaged.
So unless it's possible to do this somehow through packets and windower, it looks like there aren't any other options. :/