Beware - long question with hopefully a simple answer!
Hello community! I'm new to Zoho mail, so please be gentle if my question is a dumb one.

I  originally had one domain (we'll call it companyA.com) and I have two people in the company, lets call them Jane@companyA.com and Joe@companyA.com

I wanted Jane and Joe to be able to receive emails sent to info@companyA.com, support@companyA.com and orders@companyA.com, and I also wanted them to be able to send-as those addresses... so I set up a group (called orders@, and added info@ and support@ as aliases to that group), I then allowed Jane and Joe as members of the group. That all worked perfectly (although I'm not sure if it was the best way!)

I now have a second domain (let's call it companyB.com)
I'd like to set up the same rules for Jane and Joe, so that they can receive from any of the email addresses info@companyA.com, support@companyA.com, orders@companyA.com, info@companyB.com, support@companyB.com, orders@companyB.com, and can also send from them.

SO - I added the second domain, created a second group using the second domain and added jane@CompanyA and Joe@CompanyA to the group - which seems to be ok... 

I added an alias to Jane@CompanyA of Jane@CompanyB - that worked fine. I tried to add an alias to Joe@CompanyA of Joe@CompanyB, but that's failing with a red box around the alias username and the number Z112

I have two questions:

1) Am I being dumb about how I'm setting this up, would it be simpler just to make CompanB.com and alias of CompanyA.com, and would that fulfill what I'm trying to do?

2) What is wrong with adding a user alias to Joe@CompanyA, what does Z112 to relate to?

If you read this far, thank you!
If you can point me in the right direction, thank you again!!