Yes. Each time we create an announcement, we are given the option of who will receive it. 

By default, all members are included in all email and text announcements. 

To send to a subset of members in the group, remove the "All members" option and start typing the names of the members you want to include. If sending an announcement to a group within an organization, you can also click in the recipient field to bring up a list of sub-groups as recipients.