Ability to change group member at any stage...
Kindly add option to change the group member. For example, person "X" with email id "X@yahoo.com" has been added to the group "Alps Trek" and also some expenses has been added in the group with say equal distribution, it should still be possible to add same person "X' with email id "X@gmail.com". Ultimately dropping person "X" "X@yahoo.com" and transferring expenses on her name to same person "X' with email id "X@gmail.com".
Sorry for the trouble! Splitwise allows you to change a person’s email address if they haven’t claimed their account yet, though that may not be clear on mobile (you have to do it by going to that friend’s page and opening the “Friend settings” screen, instead of doing it from the group settings screen). Hopefully we can update our group settings page on mobile soon, so that you can update a person’s email address directly from that screen.
Once the other person has already accepted their invite, you can no longer update their email address, since it’s their account at that point. Hope that helps!
The useful functionality would be to swap one person's entire Splitwise history with another person -- this happens rather frequently where the wrong email was used for a while and needs to be changed. It seems the only way to do it now is to manually switch each cost entry historically.