Multiple SMTP domains in one organization using one edge server and same IP address

I have the following scenario:

There is one forest domain and one child domain. In the forest domain, exchange server 2013 (CAS MBX) and exchange edge server 2010 as an SMTP relay installed, and in a child domain there are only exchange server 2013 (CAS MBX) installed. Each has its own SMTP address. Because the child domain does not have the internet facing, then mail flow will be pass through to the edge server in the forest domain. For MX records will be pointing to the same IP but different domain.

Can I can use such a scenario?

Please enlightenment.

Thank a lot