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There is definitely no simple answer I can provide here as it will depend on a variety of factors. Things like how your business is set-up, the financial and legal implications of separating or not separating the businesses, license requirements and even regulatory requirements in your jurisdiction will all matter.
The best thing to do here is to consult both a legal expert and business consultant in your area to determined the best course of action with managing four different businesses - either as different branches under the same brand or as separate entities.
On Shopify's end of things we certainly allow you to create multiple stores with the same email address and connect your preferred bank account for payouts. Technically you could use the same bank account for these deposits tied to the same business, but I do strongly advise that you fully explore any ramifications of doing so for liability and tax purposes.
For the immediate future, you may even want to start off with a focus on one store to save on monthly fees while you grow your business and customer base. This will ultimately end up being a very personal decision and it's a good idea to explore all avenues.
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