Changing Members but keeping lvls.

I have more than four characters and want to be able to change party members whenever the player chooses.
How would i go about doing this without reseting the characters lvl back to 1. Is there a script to it? or something simpler?
A Script would be great if anybody had that.

Thanks.

Make sure the 'Initialize' box isn't checked when adding the member from the change party member event.