easy...
conditional a para event with
if key(your call) is pressed then
-would you like to switch characters?
-show choices yes,no
--if yes
---if switch(hero of choice in case you want to "find it") is on then
----would you like to use (hero) as your character?
----show choices: yes,no
-----if yes then
------add party member (hero) remove party member (other hero)
-----else
------if switch (another hero) then
.
.
.
and so on
if no then
*nothing*
it's easier than it sounds so inaru puts it, the thing is to think about how you do it, right inaru? -.-