The problem
Two brands in the same group serve different clients. They must also exchange information. The obvious solution is one tool for both brands: one portal, one set of accounts, one invoice. That solution also stops each brand from making its own decisions.
The reasoning
We decided not to merge the two portals. A brand must change its offer, its prices or its identity without permission from the other brand. A failure in one brand must not stop the service of the other brand. The cost is clear. We must define exactly what the two brands tell each other.
The effect
Each brand keeps control of its product and of its data. A failure stays local. If one brand is sold, there is nothing to separate.