Hi
Yes, we can add 10 member accounts under your Subscription.
Please follow the below Steps.
Method I
1.Sign in to MSN with the Primary email account
2.On the Help & Settings menu, click Accounts & Billing.
3.Click Add member accounts.
4.Create a new member account
Method II
You can also go to https://membercenter.msn.com
Sign in with the primary email account
Click on Secondary User Management
Click on Add a Member
Note:-After Adding the member account it will take few minutes to display that account on MSN Welcome Screen.
Thanks
MSN Support team