One of the hard parts about being a system with loose boundaries, means that we can mostly access the memories of the others (with some exceptions), meaning keeping secrets from each other is rather difficult. Sure I could change the password for the credit card and keep the others from buying anything, but with enough effort, they'll be able to crack it. It just means communication, boundaries, and respect are more important.

[ID]

Panel 1: Ian is sitting at a desk on his laptop, saying "Oh that looks so cool! I gotta have it.

Panel 2: Jak now appears behind him, resting his hand on the chair, saying "Now we talked about this. We said no more spending this month." Ian replies, "But...but..."

Panel 3: Jak crosses his arms, "No "buts"! I forbid you from buying that." Ian grumbles.

Panel 4: Ian has a wicked smirk as he rubs his hands villianously, saying "Hehehe...I'd like to see you stop me...I know the password!"