How to add another management scope to existing role group and existing management role.

Hello Cool People,

So I have  created a custom RBAC Role with the quick details below.  First, I have created a new management role with only the "set-mailbox" cmdlet since its only adding a secondary email is all they need to do. Second, I created a Scope that is only limited to a single mailbox and lastly, created a new rolegroup and assign it with the role and scope that I created. 

Role : "Email Alias Creator"
Scope : "Mailbox1 Scope"
Group : "Mailbox1 Operator"

I hope someone kind enough can help me with me questions:

• I created the new management scope using this command that will only limit it to mailbox1@domain.com:

New-ManagementScope -Name "Mailbox1 Scope" -RecipientRestrictionFilter {Name -eq "Mailbox1"} 

• I created a group and assign the custom role and the scope that I created using:

New-RoleGroup -Name "Mailbox1 Operator" -Roles "Email Alias Creator" -CustomRecipientWriteScope "Mailbox1 Scope"

I hope someone can shed some light on my queries below:

1. Is there a way I can edit the "mailbox1 scope"? or is there a way I can add another target mailbox for that scope for example {Name -eq "mailbox2") and have it assigned with the "Email Alias Creator" role and  linked to the Mailbox1 Operator group?
2. In doing -RecipientRestrictionFilter {Name -eq "Mailbox1"} ,Should I specify Mailbox1@domain.com or should I use the display name for the mailbox?

Thanks in Advance for any post and response to query,

Best!