Issue with welcome message on instance with multiple brands

Dear Zendesk team and dear community.

We have a use case that I can't fulfill, and I go to this whole beautiful community to see if anyone is experiencing the same thing or if the Zendesk team has any additional workarounds.
I will describe the case below (please be patient, it is long):

* In my instance I have 5 brands (A, B, C, D and E), each brand represents a different company and brand A was the first to be created in the instance

* The mark To the tickets of your clients enter only by form (guide activated)

* In brands B and D, your customer's tickets enter only through the zendesk bot in messaging format where we have configured a transfer step to an agent (without activated guide)

* Brand C, the tickets of your clients enter via form and bot in messaging format (both from zendesk) (with guide activated)

* The E mark, the tickets of your clients enter via bot messaging format (with guide activated)

* Each brand has a different mail and a different design that represents your business

* The instance is open, anyone can create a ticket

* Each new end user receives their welcome email to register when they have created their first ticket

The problem I have is that when an end user creates a ticket for the first time (for example from brand B through the bot form) the welcome email that reaches the end user is sent from any of the other brands, in this case of mark A, but never from the march where I create the first ticket.

Then the end user finds himself with two emails, the welcome one that was sent by brand A and the email corresponding to the creation of the ticket that was sent by brand B. The same happens with brand D, C and E.

Imagine what the client might think...? You are writing to a brand and you get a welcome from another brand... (the situation is a bit messy).

We tried to change the default brand, the default mail, the default agent route, but we have not been able to get the welcome to be provided by the corresponding brand.

We get to the point of only leaving two marks, but the same thing happens.

I would like to know if this use case has happened to anyone, because we did not find any way to route the welcome messages by the corresponding brand.

First of all, I attribute it to something that we are missing from configuring, but I am afraid that this case could be a big Zendesk bug.

We remain attentive to any comment.
Greetings from the southern cone!