I would like to know is this account created for simulation or consider a first ECOM account in TH?
If it is a first ECOM account that need to implement in TH, please raise new FBR for every interfaces just like normal procedure on new project. If only for simulation, you may use back the previous FBR and mention the which account will be using the interface. Please update for all the FBR instead just 1 FBR which you done it.