Certificates for Exchange and Lync

Hi all,

I have three SMTP domains in my domain xxx.com.sa:

1. xxx.com.sa

2. yyy.com.sa

3. zzz.com.sa

And I have Lync also with the theree SMTP domains above as well, my question is the following:

Can I buy a UC wildcard certificate that include all the above, install it on my Exchange CAS servers, TMG server and Lync Edge server that will make sure Exchange and Lync are working fine? Do I need to add the Exchange mailbox and CAS servers as SANs in this certificate?